The invention discloses a system and a method for starting an engine of an HEV (Hybrid Electric Vehicle). The system comprises a high-voltage battery, the engine, an ISG (Integrated Starter and Generator), a BMS (Battery Management System), an EMS (Engine Management System), a motor controller and an HCU (Hybrid Control Unit), wherein the engine is in rigid connection with the ISG, the energy of the ISG is obtained from the high-voltage battery, the HCU is used for controlling the ISG through the motor controller, battery information is obtained through the BMS, engine information is obtained through the EMS, the HCU is used for determining the starting target rotating speed, the oil injection starting and/or ignition rotating speed and whether to request to reduce the battery discharging capacity limit in a short time by the BMS or not through the battery information and the engine information, the motor controller is instructed for dragging the engine and the ISG to the target rotating speed and maintaining the target rotating speed, and the HCU is used for determining whether the starting is finished or not through a torque which is fed back by the motor controller and an engine state which is fed back by the EMS. According to the system for starting the engine of the HEV, disclosed by the invention, the system does not comprise a traditional starting engine with 12V/24V low voltage, and the ISG is also utilized for starting the engine under a low-temperature environment.