The invention relates to the field of printing processes, and specifically relates to a direct-injection printing process adopting water-based UV cured ink. The used direct-injection printing device comprises an installation seat, wherein ultraviolet lamps are fixedly installed around the installation seat separately; an ink injection pipe is connected into the installation seat in a sleeved manner; the bottom of the ink injection pipe penetrates through to reach the lower surface of the installation seat; and a lamp pipe is connected into each ultraviolet lamp in a sleeved manner. Through arrangement for an adjustor, a triangular plate is enabled to carry out closing action by rotating a drive gear, the drive gear is rotated by different degrees to adjust a luminous flux, so that passingultraviolet rays are ideally adjusted, influence on curing for a coating layer with a color is more obvious, and the curing speed and curing depth of the printing ink are increased; through arrangement for a light diffuser, conversion for the divergent light rays of a point light source to parallel light rays is facilitated; and in combination with a reflector, re-refraction for inclined light rays which pass through the interiors of the lamp pipes and are unbalanced due to the interference of mercury molecular reflection at the moment that the ultraviolet ray makes critical contact with ink to be cured, is facilitated.