The wooden artifacts excavated in Gansu are typical rotted wooden objects, based on the shapes and structures of the wood. The woods used were identified as wood from Picea spp., Sabina spp. and Abies spp. Based on the shape, structure, and effecting issues the wooden artifacts, it is concluded that after the first fundamental change, when the wood moisture content was well below the fiber saturation point, the artifacts experienced a second fundamental change stage, when wood moisture content was close or slightly higher than the moisture content balance point. The change during the second stage is devastating for the artifacts. The microstructure of the wood observed by cross-sectional microscopy and by scanning electron microscopy. These results match those of' the different decay stages of the objects. A piece of coffin wood excavated with other rotted wood artifacts was selected as a research control subject to measure its chemical compositions, volume, weight, moisture content and mechanical properties. It was found that more than 50% of the wood fiber had degraded and that the wood had a moisture content of 10.5%. In addition, the woods mechanical properties have declined significantly, with its density being about 60% that of normal density of the wood. It is concluded that: 1) the shape and structural condition of the rolled wood match its condition us observed by the cross - sectional method and SEM; measurement of the material composition, volume, weight and mechanical properties provide solid support for the analytical results; 2) the main cause of the shape and structural change of the rotted wood is its wood moisture content, a value that changes with the surrounding environment and reflects the material properties of the rotted wood; 3) the fiber saturation and moisture content balance points are very important physical parameters that could affect the shape and structure of the wooden artifact; 4) depending on the properties of the rotted wood artifacts, their preservation should be done without direct contact with water. The moisture content of the wood artifacts should be strictly controlled. A stable and constant environment is crucial for the preservation of rotted wood artifacts.