We analyzed the variations characteristics of Poisson ratio in crustal media before and after the 31 moderate-strong earthquakes in Xinjiang by using P receiver function,stacking method of receiver function and time window sliding method. The results show that there are 4 events in 5 earthquakes with M_S6.0 and 5 earthquakes in 5.0 ≤ M_S ≤ 5.8 earthquakes have observed a significant low value anomaly in the Poisson's ratio before the earthquake. The morphological characteristics are of "V" type,and the earthquake occurred at the end of the formation of the"V". After the earthquake,the Poisson ratio continued to rise. According to the crustal Poisson's ratio of the descending process,variations process,seismic time,and the magnitude and epicentral distance of the earthquakes,it is considered that under the existing network density in Xinjiang,the P-wave receiver function can be used to monitor the dynamic change of Poisson's ratio of underground medium in the defense zone. Earthquakes with M_S ≥ 6.0 are limited to stations within 100km and with M_S ≥ 5.0 are limited to stations within 50km of the epicenter. In the performance of the analysis of crustal Poisson's ratio slip,it is necessary to select the good correlation and Moho surface reflection converted wave (Ps) with clear and consistent receive function. Due to the complex crustal structure in Xinjiang and the different receiving functions of different seismic stations,it is important to select the appropriate tracked stations. Combined with the analysis of 31 earthquake cases in this paper,it is considered that the selection of station are Yamansu(YMS) in the eastern part of Xinjiang,Kumishi(KMS) in the middle of Xinjiang,Wusu(WSU) in the northern Tianshan Mountains,Wushi(WUS) in the middle of the southern Tianshan Mountains,Bapanshuimo(BPM) in the Kalpin block,and Yutian(YUT) in the end of Altun break. It is feasible to choose 5 seismic stations for dynamic monitoring of the Poisson's ratio change of the underground medium in the nearby area. Although earthquake in the Kashgar-Wuqia intersection is frequent,due to the complex phase of the Moho surface reflection wave Ps in the receiving function of the Wuqia station,maybe it is not suitable to conduct slid analysis for the Poisson's ratio variations before and after the earthquake with M_S5.0.