Abstract: Based on precipitation data collected at 486 observational stations in China and NCEP/NCAR reanalysis atmospheric circulation data from 1958 to 2014, the relationship between summer precipitation in China and winds at low and high levels is investigated first. A new East Asian subtropical summer monsoon index is then defined using 200 hPa zonal winds that are closely related to three types of summer rainfall pattern in eastern China. The results show that the new index can well reflect not only the integrated impact of circulations over the high and low latitudes, but also the characteristics of summer precipitation difference between northern and southern China. In strong East Asian summer monsoon years, the upper westerly jet strengthens, cold air activity is located to the north, the low-level West Pacific subtropical high intensifies and shifts northward, resulting in strong southwesterly flows over eastern East Asian, and pattern Ⅰ rainfall occurs in eastern China; the circulation pattern in weak East Asian summer monsoon years is opposite to that in strong monsoon years, and pattern Ⅲ rainfall occurs in eastern China. Compared with the existing East Asian summer monsoon indices, the new index has a great advantage in reflecting the precipitation difference between the north and south of eastern China.