Abstract: The present invention relates to a photo-induced cationic polymerized pure vegetable oil-based polymer and a preparation method and use thereof. The preparation method comprises the following steps: mixing a dry oil, an epoxy vegetable oil and an initiator uniformly, irradiating to initiate a photo-curing reaction, and then placing at ambient temperature, and continuing to a heat-curing reaction so as to obtain a photo-induced cationic polymerized pure vegetable oil-based polymer. In the present invention, vegetable oil resources which are low in price, widespread, and easy to regenerate are used to prepare the pure vegetable oil-based polymers instead of the fossil-derived monomers completely, thereby achieving the efficient use of vegetable oils. In the present invention, an unconventional photo-induced heat frontal polymerization technology is used to prepare the pure vegetable oil-based polymer, thereby achieving a photo-thermal dual curing reaction of a vegetable oil system without heating.