Based on the 1-second sampling data derived from 11 geomagnetic stations in Yunann Province,we calculated and analyzed spatial-temporal variations of vertical geomagnetic intensity polartzation value (Y_zh) before Tonghai M_S5.0 on August 13th and 14th,2018 and Mojiang M_S5.9 on September 8th,2019. The result shows that there exists an obvious enhancement of Y_zh' amplitude in most geomagnetic stations before the earthquakes. However,compared with the previous studies of earthquake cases,the high-value anomaly of polarization value appeared even earlier,probably 2~5 months before the earthquake. The closer the time is to the earthquake,the larger the amplitude of the anomaly may have and the longer the duration of the anomaly will be. Moreover,it is found that these two earthquakes mainly occur near the zero threshold line of the spatial contour. This may be of significance of indication for the prediction of the earthquake location in the future. Compared with the D_st index in the period of anomaly generation,the high-value anomaly was not caused by the space current system.