Shenjiamen port subsea tunnel is the first subsea passenger tunnel in mainland China built by immersed tube method. In the paper, the influence of the waves and tides on the construction of the subsea tunnel is presented, proper tube towing method and proper tube sinking method are selected on basis of mechanical calculations and analysis, proper construction window time is determined, and the key points in the towing, sinking, connection and backfilling of the tubes are analyzed. In the end, the tunnel has been completed successfully.