The invention relates to a method and instrument for detecting an oil gas recovery system of a gas station, in particular to an oil gas recovery detecting method and an intelligent detecting instrument, wherein the detecting method comprises the step of detecting the tightness, the liquid resistance and the gas liquid ratio of the oil gas recovery system of the gas station according to the programmed sequence by adopting a flow and pressure matching mode, and the detection data is automatically saved and can be printed on the spot or transmitted to a computer; and the intelligent detecting instrument comprises an anti-explosion circuit system and a closed gas path system, wherein the anti-explosion circuit system comprises a power supply source, a Roots flow sensor, a digital pressure sensor, a display screen, an input keyboard, a single chip microcomputer processing module, a data memory, a printer interface, a data transmission interface and the like, the closed gas path system comprises a flow sensor, a pressure sensor, a pipe fitting, a flexible pipe and a quick joint, and the circuit system and the gas path system are matched with a panel to be integrally installed in a box body. The detecting method of the invention is distinct, flexible, simple and convenient; and the detecting instrument of the invention has compact structure and perfect functions and can be carried, used, maintained and repaired simply and easily.