Climate warming and intensified human activities have led to the deterioration of lake environments and the degradation of lake ecological services in China over the past few decades. In northeast (NE) China, up to now, information about lake ecological changes responding to climate changes and human activities has derived mainly from short-term observations. In the present study, we choose Jingpo Lake in NE China as the study area. Sediment records and paleolimnological methods, in combination with long-term meteorological observations, were used to determine the patterns of diatom community responses to climate changes and anthropogenic disturbances. The history of diatom assemblage changes over the past 130 years was reconstructed from the sediment of Jingpo Lake. The result was then compared with other diatom records from NE China to evaluate the impacts of climate changes and human activities on diatom community shifts. Our diatom records show a distinct shift from small-type planktonic species (e.g., Cyclostephanos dubius, Cyclostephanos tholiformis, Stephanodiscus parvus, Stephanodiscus invisitatus, Discostella pseudostelligera) to a genus of heavy frustules (Aulacoseira), implying that wind strength played an important role in diatom assemblage changes before the expansion of human activities. Since the end of the 1960s, successive increases in the abundance of Asterionella formosa, Nitzschia palea, and Fragilaria crotonensis have reflected intensified agricultural activities, fertilizer usage, and sewage discharge, which have resulted in a trend to eutrophication. The meteorological observations of the past 60 years reveal obvious climate warming in NE China, especially since the mid-1970s. Previous studies have shown that diatom communities in Lake Xiaolongwan and Erlongwan (NE China) have clearly responded to climate warming, while diatoms in Jingpo Lake have not responded in a similar way. Lake Xiaolongwan and Erlongwan have similar climate conditions to those at Jingpo Lake but much smaller basins and catchments. Additionally, human activities in the catchments of Lake Xiaolongwan and Erlongwan are much less intense. Therefore, it can be speculated that the impacts of climate warming on the diatom community shift in Jingpo Lake have been obscured by intense human disturbances. Additionally, intensified human activity has become the dominant factor leading to the ecological threshold being crossed in Jingpo Lake.