Abstract: In this paper, the monitoring results of the photovoltaic support micro short pile of a photovoltaic project in Zhangbei show that the freeze-thaw pull-out force has a great impact on the micro short pile, which should attract the attention of geotechnical engineers. Through drilling, soil sampling, testing, monitoring and other means, the similarities and differences of experience method (standard look-up table method), test method (indoor frost heave rate test method) and monitoring method (in-situ average frost heave monitoring method) in judging the frost heave of cohesive soil are compared. Through comparison, it is concluded that the results of the test method and the monitoring method are similar and more reliable, while the empirical method is often not acceptable due to the special definition of water content and groundwater level. At the same time, the linear correlation between the frost heave rate of cohesive soil and other physical indicators is analyzed. It is concluded that there is no obvious linear correlation between physical indicators and frost heave rate, which reflects the complexity of the frost heave mechanism of cohesive soil, and contradicts the complexity of previous research conclusions.