The artificially imposed drought experiments based on the method of Le Tran Binh and Le Thi Muoi (1998) were conducted at Song Boi Maize Research and Seed Production Center from 2012 to 2014. Results of testing showed that combinations are the medium early maturing hybrid maize, at 104 - 111 days under irrigated and 107 - 113 days under non-irrigated conditions. In the nonirrigated conditions all the morphology traits and the yield of the combinations are reduced. In both irrigated and non-irrigated trials, all the combinations have negative Hmp of maturing. These mean that growth duration of combinations are shorter than the average of their two parents, respectively from 0.5 to 4 days. In both irrigated and non-irrigated trials, the real heterosises (Hbp) on plant height, ears of height, length, and diameter, number of kernel row, kernel per row, 1.000 kernel weight are positive. These real heterosises (Hbp) on all traits are reduced in the non-irrigated conditions. When compared to check of VN8960, combinations with highest standard heteroris are MC7 (18.7%); MC5 (13.9%); MC4 (13.7%) in the irrigated trials and MC7 (27.4%); MC5 (13.4%) in the non - irrigated trials. When compared to check of C919, combinations with highest standard heteroris are MC7 (20.6%); MC5 (15.7%); MC4 (15.5%) in the irrigated trials and MC7 (25.0%); MC5 (11.3%) in the non - irrigated trials.