It is necessary to carry out quantitative analysis for the ABS hydraulic modulator to upgrade the system performances. Mathematical modeling method for the ABS hydraulic modulator, is suggested in the view of electromagnetism and fluid mechanics. Also, an analytic method is proposed for the resultant forces of electromagnetism and hydraulic pressure generated in the real vehicle ABS. The relationships between the design factor of Inlet & outlet solenoid valve and the system performance of ABS, are investigated through the analytical precess.