Interannual and interdecadal variations of South Asia high (SAH) and the relation with the summer precipitation of China are studied by use of the NCEP/NCAR monthly mean reanalysis data and observational data at stations given by National Meteorological Center. It is found that all of the parameters of SAH except the ridge line position exist the remarkably interdecadal variations in summer. There is no significant partial correlation between the intensity and the east ridge point (ERP) of SAH when the area is stable. The simultaneous correlation shows that the significant positive correlation occurs between the location of the ERP of SAH and the summer rainfall of the YangtzeHuaihe River Basin (YHB) during 1979-2008, and this correlation has a big change through the sliding correlation analysis, turning from the negative correlation before the 1970s to the positive one. All these exhibit that the position of the ERP of SAH can be considered as a strong signal when studying the precipitation anomaly of the YHB.