A rail type switching valve includes an upper connector, a constant pressure valve portion, a displacement piston portion, a rail-exchange mechanism and a lower connector which are connected from top to bottom in sequence and the upper connector and the other end of the lower connector are respectively connected with a standard oil pipe. The constant pressure valve portion comprises a valve seat connected with the upper connector, a valve body under the valve seat, a constant pressure spring under the valve and a sealing pad positioned between the valve seat and the valve body. An upper central pipe communicated with the upper connector is nested in the inner sides of the valve body and the constant pressure spring. A flow passing hole is formed on the upper central pipe, a switchable throttle outlet communicated with the flow passing hole on the upper central pipe is formed between the valve seat and the valve body and the throttle outlet switch corresponds to two states of setting seal and examining seal. According to the rail type switching valve, the switch of the function of setting seal and examining seal can be achieved conveniently, a pin is free of bearing a big loading force and only has the function of slipslip and guiding.