A probabilistic approach is proposed in order to study the accuracy of evaluations of earthquake damage to ancient wooden buildings. Two factors, the structural damage index and the maximum drift angle, are considered in establishing the evaluation model. The evaluation of earthquake damage to woodbased structures in ancient buildings is established by comprehensive evaluation of the seismic damage model. This method calculates the probability of various kinds of damage under various levels of destructive conditions by comprehensive analysis of current conditions and experimental data. The actual damage condition during an earthquake should correspond to the calculated condition with the largest probability. This method was verified by studying two ancient wooden buildings with different kinds of structural damage incurred during the Wenchuan Earthquake. As a result, the rationale and validity of the model were demonstrated. The model could be used to accurately predict the seismic damage to the ancient wooden building and provide theoretical information for the strengthening of ancient buildings to minimize the damage during future earthquakes.