Characteristic parameters of infrared photodetectors can not only represent the detection performance, but also can act as the key basis to improve the device performance in the development process. The measurement and analysis of characteristic parameters are important means to adequately evaluate the infrared-sensitive materials, fabrication technology and device performance. The definition, measuring and calculation methods of characteristic parameters of single-element infrared photodetectors are systematically reviewed, especially the analysis method of characteristic parameters. The analysis of characteristic parameters is that, device characteristics which cannot be directly measured can be analyzed from the directly-measured characteristics. Characteristic parameters such as activation energy, surface leakage current and lateral diffusion length of the carrier are analyzed based on directly-measured dark current. This work has enriched the evaluation and optimization methods of infrared photodetectors.