Twice investigations around Hangzhou area show that ⁷Be content average in the ground air is 5.9 mBq·m^-3. The content of ⁷Be is the highest in autunm-winter period reaching about 7.7mBq·m^-3; the next is in spring about 6.2mBq•m^-3; then is in the early summer about 5.7 mBq·m^-3, close to the annual average level; and the lowest in a year is in summer-autumn period with a value about 3.8 mBq•m^-3. Exhibited is a decreasing trend from autumn-winter period to summer-autumn of the next year, which is negatively correlated with the variation of the seasonal rainfall in Hangzhou area. But this trend is different from that reported by UNSCEAR: it is the highest in spring and the lowest in the late autumn, which is based only on ⁷Be falling down from the stratosphere. However, the present investigation shows that the seasonal rainfall is the main factor influencing the variation trend of ⁷Be content in the air.