Abstract: In order to improve the energy-saving design of external walls of timber structures, this paper summarizes the research status of thermal and hygrothermal performance of external walls of timber structures in China and overseas, introduces the latest achievements of thermal and hygrothermal performance of it, both with the advances in theoretical and numerical simulation of the thermal and hygrothermal performance. The paper also proposes theoretical calculation of wall heat transfer coefficient, thermal inertia, heat storage coefficient, attenuation multiple, delay time, window-to-wall ratio, effective heat transfer coefficient and other parameters; tests the basic parameters, thermal properties and wet property parameters to provide effective material data for simulation analysis; secondly, carrys out on-site measurement of heat transfer coefficient of timber structures wall at different periods, explores the measured values and theoretical values of heat transfer coefficient at different periods; Through real-time monitoring the changes in temperature, humidity and moisture content of external walls of timber structures, analysing its trend with time; using WUFI 6.0 software to simulate thermal and hygrothermal performance of timber structures in different periods, predict the trend of the heat transfer coefficient, temperature, humidity and moisture content of the timber structure walls accuratly and reliably.