A quick release coupling device for a linear guideway comprises a rail, a slide block, a pair of end caps and a pair of connectors. Each of the end caps has a through hole in which are annularly arranged a slant rotary abutment surface and a plurality of grooves. The connectors each has an end fixed to the slide block, and another end of the connectors is defined with a wing-shaped portion, the wing-shaped portion has an abutment surface for mating with the rotary abutment surface of the end caps.