The invention relates to a heating control method and system during direct-current fast charging in the low temperature environment. The method is characterized by comprising the steps S1, after charging handshaking is carried out with a direct-current charging pipe, a major loop and a charging loop relay are closed, and after a heating request of a whole vehicle controller is received, S2 is executed; S2, a charging mode is set as a constant voltage mode, and after setting is completed, the whole vehicle controller is requested to start a heater; S3, it is judged whether or not the heater isstarted to work and a high-pressure de-energizing request of the whole vehicle controller is received, if yes, S4 is executed, and if not, if the time T is exceeded, S5 is executed; S4, a main positive relay and main negative relay of a battery pack are disconnected, constant voltage power supply is carried out on the heater, and when the minimum temperature point of the battery pack reaches a settemperature, the whole vehicle controller is requested to stop heating, and S5 is executed; S5, a charging mode is set as a constant current mode, and normal charging is carried out in the constant current mode. Compared with the prior art, the heating control method and system can avoid the situation that the current flows into a power battery during heating.