The utility model discloses a safe connecting device suitable for an operation vehicle and an oil well mouth, which comprises a vehicle connecting pipe and a well connecting pipe, the right end of thevehicle connecting pipe is connected with the left end of the well connecting pipe through a flange plate, a thermometer and a sewage draining exit are arranged on the vehicle connecting pipe, a sewage draining valve is arranged at the sewage draining exit, and a pressure gauge is arranged on the well connecting pipe. And the left end of the vehicle receiving pipe is connected with a hot water outlet port of the operation vehicle. The right end of the well connecting pipe is connected with a wellhead casing pipe through a threaded coupling. The hot water operation vehicle can be convenientlyconnected with an oil well mouth, the temperature measuring hole, the blow-down valve and the pressure gauge are arranged, relevant production data during operation can be mastered in real time, and safe production is guaranteed.