The invention relates to the technical field of locomotive or motor train unit detection, provides a method, a device and a system for detecting an adhesion coefficient, and aims to solve the problems that the detection cost of the adhesion coefficient of a locomotive or a motor train unit is high and the waste of resources is high in the prior art. The method comprises the following steps of: acquiring real-time control parameters and operating parameters on the running locomotive or the running motor train unit, and storing the control parameters and the operating parameters in an index file according to time sequence; when the operating parameters of the locomotive or the motor train unit reach a predetermined condition, transmitting the index file to a remote computer; and calculatingthe adhesion coefficient of the locomotive or the motor train unit according to the index file by the computer. The control parameters and the operating parameters of the running locomotive or the running motor train unit for the calculation of the adhesion coefficient can be detected by the method, so that the calculated adhesion coefficient is more reliable and the problem that a test train occupies a railway and affects normal running because a large amount of special experiments are required to be carried out on the running railway in order to acquire the adhesion coefficient in the priorart is solved.