The present invention provides a multichannel parallel light emitting device comprising a semiconductor cooler, a cold surface of the semiconductor cooler completely covers the area of a hot surface, and when the hot surface and the cold surface are horizontally disposed, a horizontal distance is reserved between the edge of the cold surface and the edge of the hot surface, and a positive electrode and a negative electrode are fixed on a second surface of the cold surface. The semiconductor cooler with the above structure is disposed in a sealed BOX of a BOX package, the bottom surface of the inner wall of the BOX package is provided with a groove for mounting a semiconductor cooler, a hot surface of the semiconductor cooler is fixed at the bottom of the groove, an insulating low thermal conductivity sealing ring is disposed between a lower end of a cold surface of the semiconductor cooler and the BOX package, so that the BOX package, the insulating low thermal conductivity sealing ring and the cold surface of the semiconductor cooler form a closed space, so as to achieve the TEC local hermetic effect, a water-proof film is not required for the TEC, and to ensure the TEC can work in a non-hermetic environment.