Xiang'an tunnel on East Passage Route in Xiamen, whick is now under construction, is the longest subsea tunnel in China. There exist great technical difficulties and risks in the tunnel construction. The article makes a summary of and analysis on the important and difficult aspects of the tunnel construction technology, as well as the technical problems that have so far occurred during the tunnel construction. The article recommends some aspects to which special attention should be paid during the construction of the tunnel. The article also provides some comments made by the author on these mentioned aspcts.