The invention discloses a field pressure calibration test valve and a test method for railway vehicles. The test value comprises a valve body and two connector bodies. The valve body is T-shaped and is provided with three interfaces. The two end interfaces of the valve body are an air pipe interface and a to-be-calibrated pressure gauge interface, respectively. The air pipe interface is used for being connected with a main blast line of a train. The to-be-calibrated pressure gauge interface is used for being connected with a to-be-calibrated pressure gauge. One connector body is fixedly arranged in each end interface. The center of each connector body is coaxially provided with an axial shrinkage hole and two conical cavities, wherein the axial shrinkage hole is arranged between the two conical cavities and is connected with the conical tips of the two conical cavities. The intermediate end interface is coaxially provided with a first step and a second step. According to the technical scheme of the invention, the field rapid pressure calibration for railway vehicles is realized. Detection difficulties in severe working environments (such as gas pulsation, unstable gas flow and the like), can be effectively overcome. Meanwhile, the field detection accuracy of a pressure gauge and the detection working efficiency of the pressure gauge are increased.