Lithium-ion batteries (LIBs) preheating is essential to restoring their power performance in cold weather. To make full use of the heating potential of pulse discharge and achieve the balance between heating performance and equipment cost, experiments are developed to explore the effects of average (avg) current, rms current, pulse frequency, and state of charge(SOC) on the temperature rise during preheating. It was found that within the frequency of 1kHz~10kHz and current rate less than 1C, which is most probably applied in practice, the heat generation was affected by all the factors above, among which the avg current had the highest impact. Entropy heat produced was more than the Joule heat produced and was the main contributor to the temperature rise. Therefore, it cannot be overlooked in heat generation model and simulation. As it varies greatly with the SOC, the temperature rise rate will be inconsistent when the DC pulse discharge is in the application, which will cause the user to experience an unpredictable preheating time.