Abstract: A method for improving fire prevention performance of a vehicle-carried data recording device and a protection device thereof are provided, where the method includes: mounting the vehicle-carried data recording device in a water-proof shell in a sealing manner; mounting the water-proof shell in a mounting space enclosed by an upper constant-temperature water shell and a lower constant-temperature water shell; injecting a liquid into the upper constant-temperature water shell and the lower constant-temperature water shell; mounting a constant-temperature water shell composed of the upper constant-temperature water shell and the lower constant-temperature water shell in a fire-proof box; and packing the fire-proof box in a protective housing with heat dissipation holes to prevent a data recording device from being damaged when the vehicle is damaged by the action of an external force.