Aiming at the cracking problem of large volume and irregular structure concrete during ship lock construction period,relying on the Jiuweigang Second-line Ship Lock engineering,we simulate the effects of MgO expansive agent and insulation measure on the temperature field,stress field and the cracking risk of sidewall concrete in lock chamber,and monitor the temperature and deformation histories of the actual structure concrete.The results show that the addition of MgO expansive agent is one of the effective measures to reduce the shrinkage and crack risk of ship lock concrete during the construction period,when proper insulation measure is taken at the same time,the crack risk of the surface and the center concrete casted in winter can be reduced simultaneously.The addition of MgO expansive agent almost has no effect on the temperature history of ship lock concrete,while it can reduce the shrinkage of 50×10-6~70×10-6 for the actual sidewall concrete in lock chamber and reduce the shrinkage over 40×10-6 for the actual sidewall concrete in lock head corridor.