The quantitative structure-activity relationship (QSAR) of 14 phenoxybenzoic acid derivatives was studied by ab initio method at the HF/6-31G level using Guassian03 software. The optimized structures together with some characteristic and electric parameters of the title compounds were obtained; some stereo-parameters were calculated by HyperChem software. Stepwise multiple regression and principal component regression methods are adopted to establish multi-parametric models between biological activity and parameters. The results indicated that the lager Ehomo, M, V and LogP, the smaller Elumo and S, and the higher biological activity. A theoretical direction was provided to synthesize some compounds with high activity. The quantitative structure-activity relationship (QSAR) of 14 phenoxybenzoic acid derivatives was studied by ab initio method at the HF / 6-31G level using Guassian 03 software. The optimized structures together with some characteristic and electric parameters of the title compounds were obtained; some stereo-parameters were calculated by HyperChem software. Stepwise multiple regression and principal component regression methods are adopted to establish multi-parametric models between biological activity and parameters. The results indicated that the lager Ehomo, M, V and LogP, the smaller Elumo and S , and the higher biological activity. A theoretical direction was provided to synthesize some compounds with high activity.