Study on spatiotemporal variations of vegetation greenness, characterized with greening or browning, can contribute to the understanding of changes in ecosystem structure and function, which helps formulate ecosystem management strategy for climate change mitigation and adaptation. Dramatic changes in temperature and moisture in a context of global climate change are significantly influencing vegetation greenness, but it remains uncertain how climate warming affects vegetation greenness in the forest belt of Northeast China (FBNC) over the past four decades, and whether the vegetation greenness patterns in response to changing climate and soil moisture keep consistent during different time periods. In this study, we examined the climate change trends in FBNC from 1982 to 2020 using a global meteorological reanalysis dataset, the ERA5 reanalysis, and further investigated the influencing factors shaping spatiotemporal dynamic patterns of vegetation greenness in the Great Khingan Range (GKR), the Little Khingan Range (LKR) and Changbai Mountains (CBM) by employing the leaf area index (LAI) as an indicator of vegetation greenness. The Results indicated that the climate change trend in FBNC from 1982-2020 was characterized by warming and drying, but the temperature increasing rate slowed down after 2000. The precipitation, relative humidity and soil moisture in the central part of the study area turned to an increasing trend, especially in the LKR. The overall trends of vegetation greenness in the study area were greening. However, there was a shift in the vegetation greenness trend in 2000 detested by Pettitt test, and the increasing rate of vegetation greenness during 2000-2020 was lower than that during 1982-2000, with an insignificant trend. The areas with a decreasing trend in vegetation greenness after 2000 increased by 7.23 times, which were mainly located in the northwestern part of GKR. The drivers shaping vegetation greenness change between the two periods of 1982-2000 and 2000-2020 were not consistent, with the primary drivers of air temperature and soil moisture during 1982 to 2000. While the positive effect of air temperature on vegetation greenness diminished after 2000, and the main factors driving the increasing vegetation greenness in the central part of the study area included the rising precipitation, relative humidity and soil moisture. The main factor driving vegetation browning in northwestern part of GKR was moisture limitation resulting from decreased precipitation and relative humidity. This study gained a deep insight into spatiotemporal variations of vegetation greenness in FBNC in a context of climate change, and highlights the significance of understanding climate change impact on vegetation response for developing adaptive forestry management strategy to mitigate climate change.