Abstract: The quantitative structure activity relationship of the fungicidal activities of three small sets of 1,3-nitrogen, sulphur heterocyclic compounds against Ascochyta as Paraginsa using comparative molecular field analysis(CoMFA) method was investigated. Separate studies of QSAR models on each small set of compounds and whole set of compounds were carried out. We found that for each small set of compounds, the change of substitution on the phenyl ring will affect the activity. While as a whole, the factors that have influence the activity focus on the heterocyclic ring. The QSAR models will give some guidance on synthesizing compounds with enhanced activities.