Pogostemon cablin (Blanco) Benth was one of the most important naturally occurring base materials. The aerial part of P. cablin has been used for the treatment of the common cold, headache, fever, vomiting, indigestion and diarrhea as well as an antifungal agent in the medicinal materials of China and its surrounding region. In this study, the fungal and bacterial diversity in the rhizosphere soil, autotoxic compounds and the effects of allelochemicals of P. cablin were tested. The main results were as follows:(1) In this study, terminal restriction fragment length polymorphism (T-RFLP) technique was used for fingerprinting fungal and bacterial diversity in the rhizosphere soil sampled from the fields of P. cablin monocultured for 1 and 2 yr. The results showed that the structure of bacterial and fungal community in consecutively moncultured rhizosphere soil were different from that in control soil (no cropping soil), and varied with the consecutive monoculture years (1 and 2 yr). The comprehensive evaluation index (D) of both fungal and bacterial community estimated by principal component analysis of fragment number, peak area, Simpson index, were higher in control soil than that in 2 yr monoculture soil. Evenness index decreased from control to 2 yr monoculture soil. Shannon-Weiner index of bacterial community was significantly lower in 2 yr monoculture soil than control. Both Simpson and Evenness index of fungal and bacterial community were affected by soil properties. All these suggested that consecutive monoculture of P. cablin could be result in a series of changes to soil properties and the diversity of both fungal and bacterial communities in the rhizosphere soil.(2) The effects of allelochemicals and aqueous extracts from different P. cablin parts and rhizosphere soil on growth parameters, leaf membrane peroxidation and leaf antioxidant enzymes were investigated in patchouli. P. cablin seedlings were incubated in solutions containing allelochemicals and aqueous extracts from different patchouli parts and its rhizosphere soil at several concentrations. Firstly, the growth parameters were significantly reduced by the highest concentrations of leaves, roots and stems extracts (p<0.05). As compared to the control, plant height was reduced by 99.80% in the treatment with leaves extracts (1:10). The MDA content increased greatly when patchouli seedlings were subject to different concentrations of leaves, roots and stems extracts, meanwhile, the SOD and POD activities showed a increase trend at the low concentration, followed by a decline phase at the high concentration of roots and leaves extracts (1:10). What’s more, leaves and roots extracts had a more negative effect on patchouli growth than stems extracts at the same concentrations. Secondly, the total fresh mass, root length and plant height were greatly reduced by the highest strength of soil extracts. Their decrement was 22.70%,74.90%,33.10%, respectively. Thirdly, growth parameters and enzymatic activities varied considerably with the kinds of allelochemicals and with the different concentrations. Plant height, root length and total fresh weight of patchouli were greatly reduced by p-hydroxybenzoic acid (200μM), and their decrement was 77.00%,42.00% and 70.00%, respectively. Finally, three useful measures on reducing the autotoxicity during the sustainable patchouli production were proposed.(3) The autotoxic compounds from rhizosphere soil of P. cablin were isolated and identified by GC-MS in this paper. The result showed that a total of 11,30 and 45 compounds were identified, accounting for 63.25%,64.75% and 70.57% of extracts from control soil,1 yr monoculture soil and 2 yr continuous monocultures soil, respectively. The autotoxic compounds from 2 yr monoculture soil were much more than those of 1 yr monoculture soil and control soil. The accumulation of autotoxic compounds from rhizosphere soil might be one of the main causes of continuous cropping obstacles of P. cablin.(4) Rhizosphere soil samples and roots samples were collected, organic matter content, the contents of macro-elements(N、P、K、Ca、Mg)and trace element (Fe, Mn, Zn, Cu, B, Na) were determined, so that we can provide scientific basis and technical methods for solving the problem of continuous cropping obstacles of P. cablin. The results indicated that elements proportion imbalances of P/Mg, Ca/Mg, Mn/Cu, Na/Cu, P/Mn, Ca/Mn and Mg/Cu in rhizosphere soil of P. cablin are the probable factors associated with Continuous cropping obstacles of P. cablin.