Abstract: Based on the observation data from 2018 to 2020 of nine continuous observation stations constructed in Tangshan area, it is found that the annual variation of fault soil gas CO₂ is mainly affected by ground temperature and rainfall. About one month before the 2018 Tangshan Guye M3.3 earthquake, 2019 Tangshan Fengnan M4.5 earthquake and 2020 Tangshan Guye M5.1 earthquake, different degrees of abnormal changes were recorded in Zhaogezhuang, Jinzhuang and Beipo. The abnormal patterns mainly included step rise, oscillation rise and sudden jump. The maximum abnormal peak value is 3.8 times of the background value. Abnormal changes in continuous observation data may contain earthquake precursory information.