Tunnel plays an active role in improving traffic efficiency and relieving urban traffic pressure, and the diagnosis and treatment of lining diseases is a key part to ensure the safe operation of tunnel. This paper expounds and analyzes the identification criteria of lining cracks, image information collection and crack information recognition, and briefly discusses the treatment of lining diseases. The main contents of this paper are as follows: 1. Cite the hazard rating indicators of tunnel cracks in some national tunnel maintenance regulations. 2. Analyze the current mainstream ways of acquiring tunnel image information. 3. Introduce the crack identification process and give the calculation effect diagram of part of the method.