The invention discloses a greenhouse energy-saving auxiliary temperature control system, which comprises a water supply well, a main water supply pipe, heat exchange pipes, a main water return pipe and a water return well and is characterized in that the main water supply pipe and the main water return pipe are in parallel arrangement, the heat exchange pipes are vertically and uniformly connected with the main water supply pipe and the main water return pipe, the two ends of each heat exchange pipe are respectively connected with the main water return pipe and the main water supply pipe, the main water supply pipe is connected to a submersible pump positioned in the water supply well, and the main water return pipe is connected to the water return well. When the greenhouse energy-saving auxiliary temperature control system is adopted, the temperature in a greenhouse can be more efficiently and accurately regulated, the system utilizes the temperature differences between the underground water and the natural temperature for raising or lowering the temperature in the greenhouse, the great nonregenerative resource waste can be prevented, and the effect of protecting the environment can also be reached, so the temperature regulating cost of the greenhouse is further reduced, good economic benefits can be generated, in addition, the structure is simple, and the popularization and the use are convenient.