The invention relates to a composite halogen-free flame-retardant smoke suppression agent of a PVC wood-plastic composite material and a preparation method and application of the agent, which relate to the composite halogen-free flame-retardant smoke suppression agent and the preparation method and application of the agent, and aim at solving the problems that the PVC wood-plastic composite material is combustible, a great amount of smoke is produced when the composite material is combusted, the addition amount of the existing PVC wood-plastic composite material flame-retardant smoke suppression agent is large, the flame-retardant effect and the smoke suppression effect are poor, and the existing PVC wood-plastic composite material flame-retardant smoke suppression agent is harmful to the health of people. The composite halogen-free flame-retardant smoke suppression agent consists of ammonium polyphosphate, melamine, pentaerythritol and copper oxide. The preparation method comprises the following steps: I, preparing an expansion-type flame-retardant agent; II, preparing the composite halogen-free flame-retardant smoke suppression agent. The application method comprises the following steps: I, weighing raw materials; II, preparing high-temperature materials; III, preparing a premix; IV, extruding and forming. The flame-retardant smoke suppression agent solves the problems that the wood-plastic composite material is combustible, a great amount of smoke is produced when the composite material is combusted, the addition amount of the existing flame-retardant smoke suppression agent is large, the effect is poor, and the existing flame-retardant smoke suppression agent is harmful to the health of people. The composite halogen-free flame-retardant smoke suppression agent is used for resisting the combustion and suppressing the smoke of the PVC wood-plastic composite material.