A grafting device and a grafting method based on a UV (Ultraviolet Rays) adhesive are provided. The grafting device includes a workbench, a transfer mechanism, a seedling loading mechanism, a cutting mechanism, an adhesive spraying mechanism, a curing mechanism and a seedling unloading mechanism. Along the circumferential direction of the transfer mechanism, a seedling loading station, an adhesive spraying station, a curing station and a seedling unloading station are sequentially arranged. The seedling loading mechanism is configured for bearing a rootstock and a scion, and the cutting mechanism is configured for cutting the rootstock and the scion. The transfer mechanism is configured for receiving and fixing the rootstock and the scion, and transporting the rootstock and the scion intermittently from the seedling loading station, the adhesive spraying station, the curing station and the seedling unloading station in turn to obtain a grafted seedling.