The Little Ice Age is the latest and the most typical case of cold climate event, which is significant for the research of centennial climate change. The existing results of study show that, solar and volcanic activities are the main reasons for the climate change of Little Ice Age. In this paper, by using an AGCM+SSiB model, modeling experiments are made to understand the effects of the changes of solar radiation, volcanic dust, vegetation to the change of temperature and precipitation of LIA, respectively. The result shows that:the effect on LIA temperature of changing vegetation has the same scale to that of changing solar radiation and volcanic dust, while the effect on LIA precipitation of changing vegetation is greater than that of changing solar radiation and volcanic dust. This means the effect of vegetation feedback can't be neglected for centennial climate change. It is helpful to understand the mechanism of LIA climate change deeply, and it provides a new thought and method for research of centennial climate change and forecast of climatic scenario at the same time.