The embodiment of the invention provides a room temperature deviation determination method, device and system, and relates to the technical field of thermal system evaluation. The determination methodcomprises the following steps that firstly, the room temperatures of m to-be-measured points in a heating system at n time points are obtained; then, the average room temperature is determined basedon the room temperatures, wherein the average room temperature at least comprises any one average room temperature of the average room temperature at the time of j and the average room temperature ofthe m to-be-measured points at the n time points; and then, the room temperature deviation is determined based on the average room temperature and a preset formula. As can be seen, based on the embodiment of the determination method, a calculation mode of the room temperature deviation is provided, and the balance degree of heat distribution can be reflected through the room temperature deviation.