Abstract: Grain yield and its constitution traits of 30 maize inbred lines and 18 hybrids were compared between the shade wet environment and the natural environment. The results showed that, compared with those in the natural environment, individual kernel weight, ear length, rows per ear, kernel numbers per row, grain numbers per ear and 100-kernel weight of hybrid in the shade wet environment were reduced by 72.2%, 41.90%, 25.95%, 53.79%, 64.81% and 14.69%, respectively, the difference was highly remarkable; the above traits of inbred lines in the shade wet environment were reduced by 66.97%, 34.69%, 28.82%, 48.49%, 62.03% and 6.40%, respectively, the difference was highly remarkable or remarkable. According to the comprehensive shade wet tolerance coefficient and using t test, 18 hybrids could be divided into 3 shade wet tolerance groups: 5 in strong, 7 in medium and 6 in weak; and among the 30 inbred lines, shade wet tolerance distribution was: 8 in strong group, 10 in medium group and 12 in weak group.