The invention relates to the field of hydraulic system detection, and discloses a detection system and method for a hydraulic motor as well as an engineering vehicle comprising the detection system for the hydraulic motor. The detection system comprises an execution mechanism, a speed detector and a controller, and ascending or descending of the execution mechanism is driven by the hydraulic motor; the speed detector is used for detecting ascending or descending speed of the execution mechanism; and the controller is used for executing the following operations of outputting an electric signalso as to control the input flow of the hydraulic motor so that ascending or descending speed of the execution mechanism can be controlled and determining whether the hydraulic motor generates internalleakage or not according to the output electric signal and ascending or descending speed of the execution mechanism. According to the system and the method, the internal leakage condition of the hydraulic motor can be detected in real time, the corresponding actions can be cut off in time under the condition that the hydraulic motor generates the internal leakage fault so that hook gliding of a hoisting mechanism or stall of a crawler type vehicle can be effectively prevented, and then the safety of field engineering and remanufactured products can be greatly improved.