In this paper, a three-dimensional computational model of small UAV with asymmetric wing was established, then the influences of the configuration parameters on its rolling moment were studied by numerical simulation.The results indicate that the main reason for formation of fuselage rolling moment is different pressure fields that locate at the different installation sites where wing contacts fuselage; When angle of attack and velocity of flow remain unchange, the fuselage rolling moment only varies with height difference of left and right wing, and it is not affected by angle of roll and dihedral; The rolling moment difference of left and right wing is affected by the dihedral and height difference of left and right wing, meanwhile, the dihedral has an inhibitory effect on rolling moment difference generated by height difference of left and right wing; Comprehensively, the rolling moments generated by height difference of left and right wing are relatively small, and it is possible to correct them.