Aiming at the problem of surface cracks generated in the upper part of the support beam during construction of a ship lock chamber,we analyze the causes and distribution of surface cracks of the chamber based on the finite element principle,and put forward the temperature control measures.The results show that the early surface cracks in the upper part of the support beam are mainly due to the internal-external temperature difference and the restriction effect of the support beam on the newly cast concrete;under the prerequisite of controlling the concrete casting temperature,we combine the surface heat preservation and internal water pipe cooling to control the temperature difference and the crack prevention coefficient of surface points is raised to 1.40.Applying the measure in subsequent construction,no surface cracks appear,which prove a satisfactory anti-cracking effect.