A pressure withstanding test device for a hydraulic oil cylinder comprises high-pressure ball valves and a pressure meter. The four high-pressure ball valves and the pressure meter are arranged at the upper part of an internal pressure cylindrical container; and one high-pressure ball valve is arranged at the lower part of the cylindrical container. A power pressure testing pump is connected with the high-pressure ball valve a by an oil inlet rubber pipe. The high-pressure ball valve d is connected with an opening A of a double-acting hydraulic oil cylinder by a pipeline rubber pipe. An opening B of the double-acting hydraulic oil cylinder is connected with an oil storage pool of the power pressure testing pump by an oil returning rubber pipe. A supporting frame is fixed at the lower part of the internal pressure cylindrical container. The pressure withstanding test device for the hydraulic oil cylinder is simple to manufacture, is convenient and safe to operate and has low manufacturing and test cost. Due to the pressure withstanding test device, a mechanical hydraulic oil cylinder can be tested, and performance detection on various hydraulic tube pipes and various valve bodies can also be carried out.