The invention discloses a control method of heat pump unit shutdown protection, which comprises a heat pump mode, an electric heating mode and an intelligent mode. The control method can judge whetherthe compressor heating is suitable or not by determining the indoor ambient temperature and the casing pipe water inlet temperature, and if not, electric heating is used. The invention also reduces the fault rate of the compressor on the premise of ensuring the stable water temperature of the user, and is beneficial to prolonging the service life of the compressor. Moreover, the thresholds of theindoor ambient temperature and the casing pipe water inlet temperature can be set, which greatly expands the use scope of heat pump unit.