Vertical cavity surface emitting lasers (VCSEL) have the advantages of low cost, high rate, low power consumption, and easy integration, making them widely used in fields such as short-range data communication. With the increasing requirements of lifetime and failure rate as well as the growing demand of device applications, the reliability of VCSEL has received a lot of attention. It has been found that the main cause of VCSEL failure is related to the formation and expansion of dislocations. In this paper, the causes of dislocation formation in VCSEL are analyzed, and the dynamic characteristics and intrinsic mechanism of dislocation expansion are systematically introduced to contribute to the reliability of the devices.