Four arbuscular mycorrhizal fungi (AMF) inocula were produced in the sterilized soil under glasshouse conditions.Effectiveness and infectivity of the inocula were tested in pot culture with the most probable number (MPN) test method.The results indicated that biomass of inoculated plants was significantly higher than that of non-inoculated control plants (p<0.01),and the number of propagules was in the range of 95~1 400 per gram inocula.The field trials were carried out by means of producing pre-inoculated seedlings prior to transplanting.The infection rate of maize roots increased rapidly at early stage of the plant growth and then leveled off.The yield of the maize inoculated with inoculum A (Glomus constrictum),C (three Glomus species) or D (G.intraradices) was significantly enhanced (p< 0.05),and so was the content of starch and phosphorus in grains of the maize.