The invention relates to a novel outside-test hydraulic pressure test method and a novel outside-test hydraulic pressure test device. According to the invention, one end of a master manual valve is connected with a water source, and the other end of the master manual valve is connected with a water inlet port of a pressurizing pump; a temperature sensor is used for detecting water source temperature; a water outlet port of the pressurizing pump is connected to a water inlet port of a check valve; a water outlet port of the check valve is connected to water inlet ports of a plurality of gas cylinder test devices; a pressure gauge, one end of a pressure sensor, and one end of a pressure relief solenoid valve are connected on a pressure bearing hose between the check valve water outlet port and the first gas cylinder test device water inlet port; the other end of the pressure sensor, the control port of the pressure relief solenoid valve, the signal output end of the temperature sensor, and the control port of the pressurizing pump all form signal connections with a computer control center. A water outlet port of the pressure relief solenoid valve is connected with a water discharge tank through a low-pressure water pipe. According to the invention, a plurality of water jackets are connected in series, such that simultaneous testing upon a plurality of gas cylinders is realized, testing cost is greatly reduced, and testing efficiency is improved. The method and the device have the advantages of high automation degree, low cost, and high efficiency.