The invention relates to a safety protection method for a lithium ion battery electric vehicle. The safety protection method mainly comprises a two-stage response mode, wherein the first-stage response is rapid cooling during abnormal heat production and temperature rise of a lithium ion battery, and the second-stage response is efficient fire extinguishing and cooling during thermal runaway of the lithium ion battery. The first-stage response and the second-stage response adopt the same hardware design and mainly comprise a pump set, a spray nozzle, a refrigerant, a temperature sensor, a CO sensor, a control unit and the like. The method is designed on the basis of a battery pack of the lithium ion battery electric vehicle, and multi-level and all-around protection can be carried out on battery safety through cooling before thermal runaway, fire extinguishing during thermal runaway and cooling after fire extinguishing according to different characteristics in the inoculation and development process of thermal runaway of the lithium ion battery.