Heat pump system and heat pump system control method

The invention relates to a heat pump system and a heat pump system control method. The heat pump system comprises a four-way valve used for executing switching of a working mode of the heat pump system and a pressure relief component; the four-way valve comprises a valve body provided with a valve cavity, an inlet pipe, a first outlet pipe and a second outlet pipe; the inlet pipe, the first outletpipe and the second outlet pipe are arranged on the valve body and are all communicated with the valve cavity; the inlet pipe is communicated with one of the first outlet pipe and the second outlet pipe in a matching manner when the heat pump system is switched to one working mode; the pressure relief component is connected between the first outlet pipe and the second outlet pipe and is communicated with the first outlet pipe and the second outlet pipe in the period that the working mode of the heat pump system is switched; in the four-way valve of the heat pump system, the inlet pipe is switched to be communicated w