The invention discloses a testing stand of external loads of an underwater connector. The testing stand comprises a side wall and a base installed at the bottom of the side wall, wherein the side wall and the base are each provided with a plurality of groups of rack-and-pinion adjusting devices, the rack-and-pinion adjusting devices installed on the side wall are horizontally provided with a plurality of groups of hydraulic cylinders, and the bottom ends of the hydraulic cylinders are connected with tension-compression sensors for loading the external loads on the underwater connector; the top ends of the hydraulic cylinders are provided with a load connecting plate, and the hydraulic cylinders are connected with the load connecting plate for performing torque loading on the underwater connector; the rack-and-pinion adjusting devices installed on the base are vertically provided with one group of hydraulic cylinders, and the bottom surface of the load connecting plate is provided with an upper flange; and the bottom surface of the load connecting plate is provided with a plurality of leading screw adjusting devices. According to the invention, the different external loads are applied to the underwater connector so that a test for the bearing capability of the external loads is provided for connection between submarine pipelines for the underwater connector, and besides, the test period and the test cost of the underwater connector are reduced.