The invention discloses a test method for tensile capacity under the environment of high temperature and high pressure, comprising the following steps: step 1: cone-fastened typed tensile structure is arranged in a housing which has a shape that matches the shape of the tensile structure, and the housing is provided with an opening in which the liquid can flow; step 2: a bearing surface is arranged on the adapter of the cone-fastened typed tensile structure to ensure that the liquid flowing into the housing body can impose pressure on the bearing surface towards the two ends of the tensile structure; step 3: the whole body of the housing is arranged in a high-temperature and high-pressure well, leading the fluid of high temperature and high pressure to flow into the housing body from the opening of the housing, and the tensile capacity of the tensile structure is tested by the pressure that the fluid acts on the bearing surface. The test method for tensile capacity of the invention is processed in a reactor at high temperature and high pressure, which has accurate ambient temperature and pressure, good test effect, safety and reliability.