Abstract:The results of the influence of seasonal variations of temperature and sunshine on the observation pier’s stability were introduced,based on the analysis of GNSS continuous observations data from different types of observation piers in GNSS Tangshan test field.The results indicate that:1)The variation of the observation pier includes long term tendency variation and a significant annual variation which is mainly caused by seasonal changes of precipitation and temperature.2)Stability of the observation pier is affected by external environment.For instance,the annual changes of the pier in the indoor is smaller than the outdoor.3)In the current observation condition and precision,the pier with a height of 3.5 m outdoor can not reflect any diurnal periodicity motions related to the sun.