The interval multiobjective optimization objective functions and constraint functions for the optimization problem of the specific power of a certain helicopters main reducer planetary gear trains with uncertain parameters of density and friction coefficient were established. The optimal parameter interval of objective functions and the design variables were obtained by using the improved interval multiobjective hierarchical optimization method

then the helicopters optimal main reducer planetary gear trains were compared and analyzed. Finally the experiment scheme for the efficiency of helicopters main reducer planetary gear trains was designed according to the optimization results. The results showed that: the gearing efficiency was improved by 214%

while the weight declined by 62% after the interval multiobjective optimization of the helicopters main reducer planetary gear trains

and the trend of the efficiency curves was more smooth and steady under the highspeed and heavyduty working conditions

illustrating the effectiveness of the interval multiobjective optimization method used in the specific power optimization of a certain helicopters main reducer planetary gear trains.