The invention discloses a soil temperature detection device and system in a ground source heat pump and a heating system. The soil temperature detection device and system are used for detecting the problem of soil temperature balance in the ground source heat pump. The soil temperature detection device comprises a plurality of fiber grating sensors for obtaining soil temperature of different depths in a target ground source heat pump well, wherein the plurality of fiber grating sensors are arranged in different soil depths in the ground source heat pump well correspondingly; an optical fiber demodulation host for converting the soil temperature obtained by the plurality of fiber grating sensors from optical signals into electrical signals, wherein the optical fiber demodulation host is connected with the plurality of fiber grating sensors; and a data processing module for carrying out data processing on the soil temperature, wherein the data processing module is electrically connected with the optical fiber demodulation host. According to the technical scheme, temperature difference of grating test points in the same depth of each well, and temperature difference at different depths of the same well can be seen, and data support can be provided for further heat balance.