The invention provides an inlet and outlet gas confluence device of eleven-high-pressure-gas-cylinder trailer, belonging to the technical field of a gas cylinder confluence device. The device comprises a main inlet and outlet gas pipeline, NPT1 / 2'' paired screws, a four-way joint, a high pressure six-way, a converged pipeline, eleven communicating pipelines and safety emptying devices which are fixed by three stages of fixing devices; the upper end of the main inlet and outlet gas pipeline is connected with the output port at the lower end of the high pressure six-way; the output ports at left and right ends of the high pressure six-way 26 are connected with the converged pipeline; the converged pipeline is connected with the communicating pipelines 38 through the four-way joint; and the other ends of the communicating pipelines are connected with end plugs through the NPT1 / 2'' paired screws and the safety empting devices 2. According to the device provided by the invention, the device is optimally designed by adopting the reasonable confluence device and is fixed by the three stages of fixing devices, thus, the gas leakage problems caused by the fact that the assembly is hard, the confluence device is fixed insufficiently, and the connecting pieces are loose due to the low shockproof capability of the structure of the confluence device and concentrated assembly stress are solved; the inlet and outlet gas confluence device integrates the upper, middle and lower three grouped eleven high pressure gas cylinders, and is a high integration of inlet and outlet gas confluence structure; and moreover, the device is reasonable in design, convenient in assembly and disassembly, and is convenient for operation and later period maintenance.