Abstract: A simple stress analysis is performed on a 7500 tfloating crane and the features of its original ballast tanks are elaborated.By combining the practical experience with relevant theory,four sets of innovative schemes are proposed to improve the ballast tank of the floating crane vessel.Using conventional method to compare multiple schemes,four typical working conditions are selected to evaluate the four schemes from two aspects,th e total ballast load and the ballast water adjustment.And then the best scheme is picked up.In the end,rules on the optimization of the ballast tank of a floating crane are summarized.