The invention discloses a rail power supply system fault detection method and a device, a server and a storage medium, and relates to the technical field of rail transit. The track power supply systemfault detection method comprises the steps of generating an expected backflow proportion of an earth screen based on impedance and a pre-established actual backflow proportion prediction model; if the expected reflux ratio is not within the preset threshold range, generating a fault alarm prompt and transmitting the fault alarm promp to electronic equipment for displaying; according to the method, the fault alarm prompt of the rail power supply system is generated, the rail power supply system does not need to be put into use after a railway rail is built or the rail power supply system is put into use, adjustment of the rail power supply system is simple and convenient, and a large amount of labor cost and time cost do not need to be consumed.