With development of vehicle advanced driver assistant system and intelligent techniques, safer and more intelligent Integrated-Electro-Hydraulic Braking System is required to realize brake-by-wire. Thus, more and more companies and universities developed Integrated-Electro-Hydraulic Braking System to fulfill these requirements. In this paper, an Integrated-Electro-Hydraulic Braking System is introduced, which consists of active source power, pedal feel emulator and electro control unit. As a composite system of mechanic, electron and hydraulic pressure, the Integrated-Electro-Hydraulic Braking System has complex system characteristics. Integrated-Electro-Hydraulic Braking System and active power source have very different dynamic characteristics. So algorithms of hydraulic pressure control and motor control should be apart, but algorithm of them should be united in hardware to meet integration demand. At the same time, a novel motor control method based on permanent magnet synchronous motor flux-weakening control and max torque per ampere control is proposed to reduce hydraulic pressure response time. Through analysis of Integrated-Electro-Hydraulic Braking System, this paper proposed a flux-weakening method based on q-axis current feedback, the method concentrate more on dynamic response of I-EHB. The control method is tested and optimized in test rig. Compared with the previous test result, the proposed method has the advantages of quick response, the flux-weakening and maximum torque per ampere control algorithm improved response time index by 48% in 50 bar step signal and 23.5% in 100bar step signal, compared with maximum torque per ampere control algorithm. As a result, the method based on motor control is proved effective in different work conditions of Integrated-Electro-Hydraulic Braking System.