A new experimental procedure is proposed, based on instrumental variable method[1] for analyzing wall surface heat transfer process and deducing wall surface heat transfer coefficient. Indoor tests were carried out under a wide rang of conditions and the heat transfer coefficient was correlated with wind speed. The results obtained indicate that the heat transfer coefficient of wall surface varies from 8 to18 W/m2·K with wind speed ranging from 0 to 5.5m/s. In addition, the wind direction was found not to have a significant effect on the coefficient for wall surfaces.