Larix gmelinii forest is the most typical vegetation types with unique biodiversity in the Greater Khingan Mountains, and its biodiversity is unique. The ground beetle is an indicator species for the environment and diversity of forest ecosystems, as well as a key species for understanding the characteristics of environmental change and biodiversity. In order to study the temporal dynamics of ground beetle's diversity in L. gmelinii forest,and analyze the response of ground beetles to changes in time, this paper collected 1149 ground beetles of 34 species and 15 genera from 5 large plots of L. gmelinii forest during the active period from late May to late August in 2019, and the pitfall trapping method was used to collect the ground beetles. Among all of the obtained ground beetles, seven new species were discovered for the first time in the Greater Khingan Mountains, six of which were new geography record species in China. The results show that Pterostichus and Carabus were the most abundant genera; Pterostichus eximius was the most dominant species and was the most sensitive to temporal variation in this study. The main factors that caused the number of individuals and species to show a double peak in times were the diversity of habitat types in the L. gmelinii forest and the selection of the ground beetle's dormant period. The highest peak appeared in late June. The diversity and evenness index reached the peak in early July, while the diversity decreased and the evenness increased slowly in late August. The biodiversity indexes of ground beetles were found to have a low correlation. The ground beetles had extremely significant differences in their adaptability to the environment in different time periods, among which, they had higher adaptability to the environment from late June to late July. The community structure of ground beetles was very similar from late June to late July and early August to late August (I>0.75). The changes of feeding characteristics and life history strategies resulted in significant differences in the indices of ground beetles over time, while the changes of species feeding characteristics and life history strategies were greatly affected by environmental factors. The active time of the ground beetle was longer in a stable forest climate, and the ground beetle community structure was more similar. The results provide a theoretical foundation for ground beetle temporal dynamics, as well as a theoretical and data basis for the formulation of underground biodiversity conservation and management strategies in the Greater Khingan Mountains.