Many seriously weathered stone components have been found in the JianFu Palace of the Forbidden City. To evaluate the state of preservation of these stone components, the scratch width, resilience, water diffusion rate, surface and transmission wave speeds of the stone components in the JianFu Palace were tested selectively. The survey data were compared with those obtained with fresh stones. From these studies it has been shown that those stone components have weathered badly and that protective treatment will be needed. The environmental factors affecting weathering of the stone components in the JianFu Palace were also tested and analyzed. The relationship between environmental and preservation conditions of stone component is discussed and the data obtained provided theoretical support for deterioration analysis and conservation operation.