The invention discloses an oil flow speed acquiring system for a gas relay. A signal output end of a flow monitoring sensor is connected with a signal input end of an electric-quantity acquiring and recording device through a conducting wire; a voltage signal input end, a current signal input end and an oil-temperature signal input end of the electric-quantity acquiring and recording device, and an internal pressure signal input end of a transformer are respectively connected with a voltage signal output end, a current signal output end and an oil-temperature signal output end of an oil-immersed power transformer, and an internal pressure signal output end of the transformer. The oil flow speed acquiring system disclosed by the invention can measure the flowing speed of insulating oil flow in an oil-immersed power transformer body and pipelines among oil conservators, and can simultaneously record in-line and out-line voltage and current values, oil-temperature values and the internal pressure values of the transformer in real time; the system can be operated online for a long time, the recorded monitoring data can be used as a basis for searching reasons of failures, the flow speed values which are recorded when heavy gas acts provide a reference basis for the verification of heavy gas setting values, and the heavy gas setting values can be accurately adjusted.