Considering Colombo Port City project the actual situation,such as huge construction quantity,more construction process,tight construction period,this paper applies the method of numerical simulation and physical model,the related engineering case support to carry out optimization layout and structure,which is under the premise of meeting the functional requirements.The risk and measures of optimization are analyzed,and the optimization scheme can save the construction period and cost from the source.Optimization results have been approved,and it is applied to the engineering,which provides technical support for Port City project implementation.