The invention discloses a fire extinguishing 
system using a 
power battery liquid cooling device. The fire extinguishing 
system comprises a 
battery cell module, a temperature sensor, a gas sensor, a 
smoke detector, a 
flame detector, a 
water cooling pipeline, a cooling liquid 
nozzle, a cooling 
liquid injection valve, a fire extinguishing agent 
storage tank, a fire extinguishing 
management system, analarm display screen, a connecting wire harness and a battery 
management system, wherein the temperature sensor is arranged in the 
battery cell module; the 
flame detector which is in electric signalconnection with the fire extinguishing 
management system through the connecting wire harness is arranged on the outer side of the 
battery cell module; the gas sensor, the 
smoke detector and the fire extinguishing agent 
storage tank communicate with the fire extinguishing management 
system through the connecting wire harness; and the 
water cooling pipeline is further arranged on the outer side of the battery 
cell module. Through the application of a proper control strategy, when a battery is subjected to 
thermal runaway or 
combustion, cooling liquid in a 
liquid cooling system is controlled to be injected in a directional mode, the 
advantage that the 
specific heat capacity of the liquid is large is utilized, the temperature of a battery 
cell is rapidly reduced, and the 
thermal runaway or 
flame spreading speed is delayed to provide enough escape time for passengers.