The invention discloses an electric vehicle battery heat dissipation and temperature control system and method based on liquid-gas phase change heat storage. The system comprises: a phase change evaporative cooling circulation system, a heating system and a control system. The phase change evaporative cooling circulation system includes a liquid reservoir, an adsorption phase change evaporative cooling device, a communicating pipe, a gas supply pipeline, a one-way valve, a steam drum, a condensing pipeline, an electromagnetic valve, an electric throttle valve, a condenser, a reflux pipeline, and a cooling fan. The heating system includes an adsorption phase change evaporative cooling device and a heater. The control system includes: a controller, a temperature sensor, a heat flux density sensor and a pressure sensor. The system and method provided by the invention have the beneficial effects that: through real-time monitoring of the temperature of the adsorption phase change evaporative cooling device, the heat flux density and the steam drum pressure by the control system, the working temperature and temperature difference of the power battery are effectively controlled, and the thermal reliability and working life of the power battery are improved.