The invention discloses a method, a device and a system for determining system faults. The system for determining the system faults comprises various types of facilities, each type of the facilities comprises a plurality of members, and the method for determining the system faults comprises the following steps that the running state of the system is determined; when the running state is the full load, whether the system breaks down or not is determined according to the average power consumption of the system in a preset period; when the running state is the low load, whether the system breaksdown or not is determined according to the power consumption of each facility in any type of the facilities; wherein the full load is the running state of the system when all the facilities in the system are turned on; and the low load is the running state of the system when a specific number of facilities in the system are turned on, and the specific number is less than the total number of facilities. Therefore, on the premise that the cost is not increased, the health condition assessment of the facilities can be provided for a user, and whether the system breaks down or not can be determined in time, so that the effects of timely maintenance and stable operation of the unit are achieved.