Shiziyang subaqueous tunnel, a part of Guangzhou-Shenzhen-Hongkong dedicated passenger high-speed railway, is the very first underwater railway tunnel of China, also the first extra-long underwater tunnel of our country. Its design speed reaches 350 km/h. The tunnle is a key project of Guangzhou-Shenzhen-Hongkong dedicated passenger high-speed railway. Basing on the engineering geology environment and adopted tunneling technology of Shiziyang tunnel construction, the thesis introduces comprehensively design and tunneling technology of the tunnel, also puts forward corresponding technical measures. In the project, tunneling is going to be carried out by shield machine from both portals, which is also the first practice of its kind in our country.