Abstract: According to starting performance of hybrid diesel engine of ISAD technology at low temperature, the match relationship among starting resistance torque, ISG motor power and storage battery capacitance was summarized, and influence of battery capacity was studied, which were as related to resistance torque, minimum start-up speed, electrical operating characteristics, electric transmission coefficient and thermal effects. The experiment result shows that, as far as the environment temperature decreases -5℃, starting resistance torque increases 2.5 N·m; starting resistance torque increases 3-8 N·m when the rotating speed increases 50 r/min. Studies have shown that, the first fire speed of ISAD diesel engine was increased, which was up to more than 350 r/min .The starting time from 0 to fire was 0.5 s, while the idle time was only 3.1 s, which was shorter than the original diesel engine, and fluctuations in speed was small.