The invention relates to the technical field of 3D printing, in particular to mercaptan-alkene light-cured resin for 3D printing and a preparation method of the mercaptan-alkene light-cured resin for3D printing. The mercaptan-alkene light-cured resin for 3D printing is prepared from multi-mercaptan, an acrylic resin prepolymer, a reactive diluent, an initiator, an ultraviolet absorbent, a fillerand an auxiliary raw material. According to the 3D printing light-cured resin, under the existence of a photoinitiator, during printing polymerization forming, a chain transfer reaction between doublebonds and sulfydryl occurs to reduce the volume of a polymer, so that the mercaptan-alkene light-cured resin has the advantages that oxygen-free polymerization inhibition is realized, the crosslinking degree and the reaction speed can be controlled according to different vinyl monomers, and a small number of the photoinitiators are used. By introduction of mercaptan-alkene click reaction into the3D printing resin, the curing time can be shortened, the toughness and the hardness of a 3D printing material can be improved, the production efficiency is improved, and the energy utilization rate is greatly increased.