The invention discloses a device for printing laser crystal cooling heat sinks and a method thereof. The device comprises the components of a worktable, a laser crystal, a clamp, a supporting block, a laser and a powder feeder. The clamp is cylindrical and comprises a first clamp and a second clamp which abut against two ends of the laser crystal. The supporting block is fixedly connected with the worktable and comprises a first supporting block and a second supporting block. The first supporting block abuts against the first clamp. The second supporting block abuts against the second clamp. According to the device and the method of the invention, multiple layers of cooling heat sinks are printed on the surface of the laser crystal through 3D printing technology, thereby realizing close combination between the laser crystal and the cooling heat sinks and remarkably improving heat radiation effect of the cooling heat sinks.