Abstract：The determination of the cover thickness of the submarine tunnel is very important，because it will be very dangerous if the cover thickness is too small，whereas the length，slope gradient and cost will be increased after a larger cover thickness is chosen. At first，the reasonable cover thickness for submarine tunnel of Chaotianmen in Chongqing is proposed by comparing this tunnel with some domestic and foreign well-known submarine tunnels. According to the Technical Specification for Construction of Highway Tunnel，a new concept of standard tunnel is put forward. Based on the actual situation of Chongqing Chaotianmen tunnel，by comparing the crown displacement and the principal tensile stress of standard tunnel and this tunnel in different cover thicknesses，the reasonable cover thickness is finally put forward.
