The wharf beams have cracks due to the shrinkage of the concrete. Although such cracks have little impact on the safety of structures，but they provide intrusion channel for corrosion medium and have adverse effects on the durability of structure. Aiming at the problem of shrinkage cracks produced during the construction of the beam，relying on a certain wharf project，through on-site investigation and data analysis，the causes of cracks are studied. The research shows that the cracks in this project are mainly caused by the shrinkage of concrete，and the measures of reducing the water-cement ratio and adding steel bars can effectively achieve the purpose of preventing concrete shrinkage cracks.