The invention relates to a slope instability physical model test device under joint action of rainfall and traffic vibration. The device comprises a model test box with openings in the top and one side, an artificial rainfall simulation unit for providing rainfall, a kinematic simulation unit for outputting a traffic vibration load, a monitoring unit for tracking a slope instability process, and acontrol unit, wherein the artificial rainfall simulation unit is located above the model test box; the kinematic simulation unit is located at the bottom of the model text box; the artificial rainfall simulation unit, the kinematic simulation unit and the monitoring unit are all electrically connected with the control unit. The device can simulate a slope instability evolution rule under single action, mutual action and coupled action of the rainfall and the traffic vibration, and also can carry out a synchronous comparison test on slope instability evolution through multiple combinations. The slope instability physical model test device has the beneficial effects of simple structure, simplicity and convenience in operation and multifunctionality, and provides a certain guidance effect for pre-warning of landslide hazards and prevention and treatment of projects.