At present, three phase MOSFET driver system is widely used in the field of new energy vehicle, industrial robot, and smart home equipment. Based on the requirements of high integration and three phase DC motor driver in the equipment systems, a three phase driver circuit with adjustable PWM duty cycle is designed. The circuit designed by commercial 0.25μm high voltage BCD technology, and the PWM duty cycle can be adjusted from 0% to 100% through the SPEED port voltage. When the ambient temperature reaches 165.1℃, the over temperature protection can be triggered. The chip is equipped with builtin PWM modulation module, charge pump circuit, bootstrap monitoring module, over temperature protection module and so on, ensuring the reliability of the circuit in the whole system. The simulation results show that the three phase driver circuit with adjustable duty cycle meets the design requirements.