A test device for a TO-CAN laser includes a test socket, a coaxial waveguide substrate, and a test printed circuit board (PCB). The test socket comprises a coaxial waveguide tube accommodating a signal output pin of the TO-CAN laser and an electric-conducting slot accommodating a signal input pin of the TO-CAN laser. The coaxial waveguide substrate is respectively connected with a coaxial waveguide pin of the test PCB and the coaxial waveguide tube of the test socket. An electric-conducting slot pin of the test socket is connected with corresponding control pins of the test PCB.