Taking the annual maximum flood peak flow, rainfall intensity, drainage area, river length, and river slope at different periods of 122 hydrological stations in Zhejiang Province as indicators, the regional regression equation is established. Then, the regression equation is used to calculate the annual maximum flood peak flow at those hydrological stations. Comparing the calculated values with observations, the results show that the relation between them significantly follows the regionalization rules. Therefore, Zhejiang Province can be divided into two flood calculation zones. Points where the calculated value is bigger than the measured focus on the areas such as the middle and upper reaches of the Qiantang River, the middle and upper reaches of the Ou River, the Puyang River, and the Cao’e River, and the points account for 69.5％ of whole points in the zone; points where the calculated value is smaller than the measured focus on the areas such as the Tianmu Mountain, Kuaiji Mountain, Siming Mountain, Tiantai Mountain, Dapan Mountain, Kuocang Mountain, and the North and South Yandang Mountain, distributing as “7” glyph, and the points account for 73％ of whole points in the zone. The result matches the zonings of plum rains (East Asian rainy season), typhoon rain, land utilization, vegetation, etc., in Zhejiang Province, which reveals that the zoning result is reasonable and the zoning method is feasible.