Abstract: A biphasic hyperbaric injector based on BLDC is designed for alternate and mixed injection of contrast medium and normal saline in the process of contrast medium injection in hospital. The driver hardware and algorithm are optimized especially for high-pressure and high-speed injection requirements. The interface APP is designed with parameter-input and real-time pressure-plotting of injector’s ports as two main functions. The whole device can realize the preset function and has high stability after testing.