Abstract: To master the suitable sowing date of cowpea for the convenience of the producers and realize the expected marketing of cowpea，we compiled the data of 16 times on the sowing date and flowering day of cowpea in 16 years to conduct their correlation and regression analysis. The results showed that the correlation coefficient of sowing date（x）and flowering day（y）was -0. 842，which reached very significant different level. Meanwhile，as the sowing date delayed，flowering day of cowpea gradually shortened. Furthermore，the model of sowing date and flowering day could be express as the following equation：y = 82. 854 - 12. 619 x + 1. 098 x² - 0. 032 x³. In practice，the flowering day of cowpea can be estimated based on the sowing date to guide cowpea cultivation，as well as to determine the sowing date for marketing.

Key words: cowpea, sowing date, flowering day, function model