The larger capacity of the DC motor, the greater relative armature current. In design, the winding form of high current DC motor usually adopts the double frog winding, and this kind of winding structure is relatively complicated, and there are many factors that affect the commutation ability of the DC motor. By using a brush with different resistivity to make sparkless commutation test in DC motor of test set, and based on comparative analysis on the test results, showed the facts that the split brush could increase the lateral resistance by using high resistivity brush, thereby the short circuit circulation of commutating winding was reduced, and brush spark was eliminated, and motor commutation was improved. At the same time, the tangential dislocation array of the brush was helpful to reduce the reactance electric potential of the commutating winding; therefore, the commutation performance of the motor was greatly improved.