Research conclusions: There are many factors that can cause the cracks．The shrinkage crack is the preliminary causes for the through crack in the secondary lining of tunnel．The temperature drop can cause the crack to develop into larger one．And the self—gravity，the construction disturbance or the uneven settlement under rock mass pressures can cause the crack continuous developing．The study shows the capacit)r of crack—resistance of concrete can be improved if the concrete is mixed with external material and high—efficient water—reduction agent．The secondary lining should be kept a certain distance from the excavated section to reduce the disturbance of excavation blast to the concrete of secondary lining．The tunnel portal should be enclosed for insulation．The joint—to-joint construction should be conducted to the concrete converted arch and the secondary lining for prevention of the harm of crack deformation caused by the converted arch construction to the secondary lining．