Replacing traditional building materials with renewable and sustainable materials such as timber can control environmental pollution such as energy consumption and carbon emission in the whole life cycle of a building, which is conducive to energy conservation and environmental protection. How to design timber structure building better is the focus of this study. This study takes timber structure building as the research object, evaluates the building energy consumption and CO2 emission with the whole life cycle concept. The comparative ecological advantages of timber structure building are obtained by comparing and analysing the brick-concrete structure building with equivalent thermal performance. Then by analysing the different spaces of timber structure building design, the design suggestions of energy saving and carbon reduction such as reducing the platform area appropriately and increasing the number of building floors are proposed when designing timber structure buildings.