Mid-infrared semiconductor lasers possess the advantages of small volume and high efficiency and have important application prospects in the field of environmental detection, space communication and military defense. However, the output power of mid-infrared semiconductor laser device is low, which limits its application in the above fields. Laser beam combining technology is an important approach to enhance the power of mid-infrared semiconductor lasers. In this paper, several beam combining methods and the latest progress of mid-infrared semiconductor lasers were introduced in detail.