According to the characteristics of aircraft subassembly, an optimal method for task balancing under resource constraints is presented. Firstly, the judgment indexes are abstracted to represent the running state of the assembling task, and mathematic model of assembling task balancing was established by available resources. Considering feature of aircraft subassembly, a fitness function is proposed based on two-stage priority targets, which are specific to task sequence and resource allocation respectively. Afterwards, Genetic-Tabu hybrid operations are executed to get the optimal solution. Finally, the effectiveness of this method is verified by applying to assembly task balancing of an outer flank.