Abstract: Compared with other motors,the brushless double-fed motor(BDFM) has its own unique advantages,especially suits for the open-loop control of loads of fans,pumps load and so on.Taking the cage brushless double-fed motor as research object,the paper established a mathematical model of the BDFM.Using Matlab/Simulink software,it analyzed the optimal voltage frequency control strategy in course of speed-regulation control in details.The strategy can make the motor run stablly in corresponding speed at the maximum power factor and the minimum converter capacity.