The invention discloses an environmental heat recovery system in a building and a control method of the environmental heat recovery system. The environmental heat recovery system in the building comprises a geothermal source heat exchange system, a hot water utilization device, an air conditioning terminal, a first water source heat pump unit, a second water source heat pump unit and multiple control valves, wherein the geothermal source heat exchange system is arranged underground, and the hot water utilization device and the air conditioning terminal are arranged in a user side in the building. According to the environmental heat recovery system and the control method disclosed by the invention, condensed waste heat produced at the inner part of the building and waste heat discharged by domestic hot water can be recycled while the requirements on cooling, heating and hot water of the building are met, the condensed waste heat can be used for preparing the domestic hot water, the waste heat of the domestic hot water can be used for replenishing geothermal energy in winter, and the environmental heat recovery system is energy-saving, convenient and fast and is widely applied to places of residences, villas, hotels, schools and the like.