In order to solve the problems of immersed tunnel maintenance, i.e. lacking of maintenance specifications and exiting blind areas of inspection and maintenance, research is carried out based on technical specifications for common tunnel maintenance and existing related literatures. Firstly, setting the typical engineering of concrete immersed tunnel as an example, the diseases of immersed tunnel are classified into three categories, i.e. main structure diseases, joint diseases and attachment structure diseases, and then all the causes and appearances of diseases are described in detail. Then from the perspective of preventive maintenance, the inspection system of immersed tunnel is proposed, i.e. besides routine inspection, regular inspection, periodic inspection, emergency inspection and special inspection, initial inspection should be contained in patrol inspection and structural safety should be monitored in realtime by health monitoring system during operation period. At last, according to development trend of immersed tunnel maintenance, the establishment of standardized maintenance system, the detection of hidden diseases and the rapid detection technology with less interference are discussed.