Abstract: To analysis the maximum load and allowable load of typical pressure bearing structure, confirm the load-bearing capacity of pressure vessels, the relationship between limit load of structure and microscopic character of typical material 16MnR, which is widely used in pressure vessels, is studied in this paper.Macrotrial method, Microscopic observation, Magnetic memory testing and FEM are used. Metallic materials-Charpy notch impact test is done to inspect the sensitivity of the impact of aging at ambient temperatures, and the results show that 16MnR has good toughness and ductility.There are five kinds of pre-strain state: mother metal, 5 percent, 10 percent, 15 percent and 20 percent.Tensile test of long board with two side holes is done, metallographic change on the surface is observed at real time, and magnetic memory method is used to discovery inner cracks.In the end, the FEM is used to simulate the test results.Results show that the Akv reduce 23.1 percent when the pre-strain reaches to 15 percent, but still above 150J;the limit load of structure and the microscopic character are closely connected, when the deformation looks like a "ravine", the structure is very close to load limits, basically.Finite element simulation results essentially match the test results;in the practical application of the pressure vessel, there is still great tap potentials about this material.