GAMIT/GLOBK software was used to calculate the observed data of about 400 GNSS sites in Yunnan and neighboring regions from 1999 to 2018. Based on the time series and velocity fields of each measuring point,kriging interpolation method was used to estimate the strain rate fields in 5 periods(from 1999 to 2004,2004 to 2007,2009 to 2013,2013 to 2015,2015 to 2018). Based on the spatial variations of surface expansion rate and maximum shear strain rate,as well as the distribution characteristics of M_S>5.0 seismic events within 1~3 years after the corresponding periods we found that the most seismic cases in following 3 years were occurred in the transition zone between extension and compression of high gradient belt,as well as the high value zone of the maximum shear strain gradient belt. Therefore,the GNSS strain rate field of each observation period has certain significance for predicting the occurrence of earthquakes in future. In this paper we also carry out high-precision data processing on the continuous GNSS data since 2011,and obtain the coordinate time series of all stations. The analysis of the strain time series of the tectonic blocks where Yingjiang M_S6.1 earthquake Nudian M_S6.5 earthquake and Jinggu M_S6.6 earthquake occurred,we find that trend changes,rapidly intensifies and turns of the strain about three months before the earthquakes may reflect the nonlinear adjustment of the stress-strain accumulation in the seismic region. The above results provide a reference for the short and imminent earthquake prediction,especially for the determination of time factors.