Abstract: The seakeeping performance of ships is an important index of evaluating ship performance. With an increasing number of instruments and weapons systems being used in shipbuilding, the issue con-cerning how to keep these systems working is of vital importance to ship designers. However, as the ship's seakeeping performance is contradictory with its speed performance, a reasonable evaluation scheme of the seakeeping performance is essential. In this paper, five sets of data of the sea-keeping performance that re-ceive most attention-pitch amplitude, heave amplitude, acceleration in the bow, the amidships, and the stern-are obtained through model tests. The hull lines are then optimized to improve the sea-keeping per-formance with the added resistance being limited within a certain threshold. Meanwhile, in order to ensure the accuracy of the tests, the response of ship motion in irregular waves is compared with the experimental values, and results show that the five indicators for sea-keeping performance of modified ships are success-fully optimized to meet the design goals.