Potato late blight (Solanum tuberosun L.) caused by Phytophthora infestans (Mont)de Bary, is an economically important crop disease in the world.Azoxystrobin is a fungicide commonly used in agriculture to control late blight.Azoxystrobin is QoI fungicide which blocks electron transfer and impairs ATP synthesis in cells.It is well known that single point mutations in target sites of pathogens can lead to Azoxystrobin resistance.In this study, we analyzed the spatial distribution of Azoxystrobin by P.infestans sensitivity in the 140 isolates of Phytophthora infestans.The isolates were collected from seven locations including one each in Gansu, Yunnan, Guangxi, Guizhou and Ningxia and two in Fujian.20 genetically distinct isolates from each population were included.Sensitivity to azoxystrobin in each isolate was measured by relative colony size in the presence and absence of the fungicide with a Common Garden experiment under four concentrations.The sensitivity in the 140 isolates ranged from 0.36 to 0.75 and displayed a continuous, unimodal distribution, suggesting other minor genes may modify the sensitivity of P.infestans to the fungicide.Significant difference in the sensitivity was found among populations by least significant difference (LSD) analysis (P <0.001) and isolates (P <0.001).Population differentiation for azoxystrobin sensitivity among the seven populations (QST =0.19) was higher than the corresponding population differentiation in SSRs (FST =0.12), consistent with selection for local adaption in azoxystrobin sensitivity.