Sizing agent and preparation method thereof, carbon fiber and composite material

The invention provides a sizing agent and a preparation method thereof, a carbon fiber and a composite material, and belongs to the technical field of carbon fiber sizing agents. The sizing agent is in an emulsion state and comprises a main sizing agent and water, the main slurry comprises the following components in parts by weight: 80-120 parts of novolac epoxy resin, 100-150 parts of epoxy vinyl resin and 10-20 parts of a surfactant. According to the sizing agent, the novolac epoxy resin and the epoxy vinyl resin are added into the sizing agent at the same time, the heat resistance and the wear resistance of the carbon fibers treated by the sizing agent can be improved through mutual cooperation of the novolac epoxy resin and the epoxy vinyl resin, and the carbon fibers can be applied to a high-temperature environment; the carbon fibers treated by the sizing agent have high interface bonding strength with epoxy resin, phenolic resin, vinyl resin and other thermosetting matrix resins, and the universality i