The timber joint is one of the most important factors that affect the global behavior of timber structures in all over the world. This paper aims at proposing a new procedure for evaluating the rotational stiffness of timber joints found in Taiwan. Firstly, dismantled surveys were conducted on five historic timber structures; the results showed that three various types of timber joints can be found in beam-to-column timber joints; a nondestructive testing method was proposed and applied on a total of 72 full-scale specimens to propose a method to classify the timber joints. The results showed that stress wave velocity and amplitude transmission ratios are feasible for distinguishing the joint types. Thirdly, bending tests were applied on these 72 specimens to obtain the bending slip characteristics and rotational stiffness of these timber joints. Statistical approach was employed to analyze the data and propose models to estimate the bending slip characteristics and initial rotational stiffness for each joint type. The results showed that the bending slip characteristics could be estimated by using slip due to rigid body motion, whereas dimensions and material properties of timber joints can help to predict initial rotational stiffness. Lastly, from the discussion previously, a reliable procedure for evaluation of rotational stiffness of beam-to-column timber joints was proposed.