With the increasing number of global navigation satellites and redundant information,the problem of the positioning accuracy and timeliness cannot be taken into account simultaneously has been raised.An optimal satellite selection model of global navigation satellite system based on genetic algorithm(GA)has been suggested.This algorithm is combined with the characteristic of geometric factor calculation model and GA.According to the users' requirement of positioning accuracy,the number of selected satellites is adjusted adaptively to ensure timeliness.The mutation crossover method is used to overcome the premature convergence of the satellite selection result caused by the intrinsic defect of GA.Experimental results show that the model can quickly select the satellite under the condition of the required positioning accuracy and improve the comfort of users.