Salvia miltiorrhiza is a wildly popular traditional Chinese medicine used for treatment of coronary heart disease and inflammation.Much of these function has been attributed to the phenolic acids, so it is worth to concern to improve the content of phenolic acids in S.miltiorrhiza.As an essential plant macronutrient, phosphorus is often deficient and thereby imposes the limitation on crop yield.To copy with this condition, plants have evolved adaptive mechanism such as increasing the accumulation of anthocyanin.In this study, we found that comparing with pi-sufficient, the pi-deficient 6,7-v medium remarkably promoted the production of phenolic acids in s.miltiorrhiza (the content of LAB,DSU,RSA,CA in treatment was 2.33,1.02,1.68 and 2.17 folds of control respectively, and the changing trend of LAB and DSU was more similar).It is believed that our findings will offer an strategy of resource-saving and environmental protection to increase the yield of active substance in herbal.Expression of key enzyme genes in phenolic acids biosynthesis pathway was increased in pi-deficiency medium, and the increasing of downstream genes was more obvious than that of upstream genes.Therefore, we deduced that pi-starvation first affected the downstream genes by some mechanism.In order to find the correlation of secondary metabolism with pi-deficiency single, we measured the expression of four SPX genes, they also increased in pi-deficiency.The expression change of SPX which belong to the early response genes to phosphrous-starvation is samilar to the key enzyme genes which belong to the later response genes during phosphorus-deficiency.We sepculated they must have some correlation.The relationship of SPX and key enzyme genes and the role they play in phenplic acids biosythesis during pi-deficiency need further studies.