The migration of phosphorus in soil is one of the key factors affecting the P use efficiency in agriculture system.Phosphorus distribution in gray desert soil from monoammonium phosphate(MAP)applied by drip -irrigation was studied by 32P isotope tracing and autoradiography technique in greenhouse. Our results showed that compared with no phosphatetreatment(CK)，drip fertigation of phosphate fertilizer increased the Olsen P in the 0～ 15 cm layer. Different proportions of 32P were found in every layers within 20 cm depth and 72.7%～ 89.5% of the 32P was retained in the 0～ 10 cm depths.The decreasing order of the migration distance of the P wasT3(0～ 20cm)>T2(0～ 10cm)>T1(0～ 5cm)，whichwas mainly attributed to the dry and wet alternation and different soil porosity at different times. The migration ofphosphorus，which was in parallel to the drip tape，was more active than that of vertical to the drip tape. The longer distance P migration was with higher P concentration in soil. The 32P migration in treatments of MAP was twice than that of the CK treatment.