This study investigates the slamming load characteristics on the ladder of the self-propelled cutter suction dredger Tianjing under head-sea conditions. The vessel’s motion responses are computed based on potential flow theory, and the slamming pressures on the ladder are analyzed using the Von Kármán and Wagner impact theories, as well as the GJB design code method. Results show that the GJB method is more suitable for evaluating hull slamming loads. Ladder slamming predominantly occurs near the waterline, and the impact loads follow a three-parameter Weibull distribution. Increase in ship size significantly reduces motion responses, slamming frequency, and pressure intensity. However, short-period waves tend to intensify slamming risks. Based on the three-parameter Weibull model and extreme value theory, the design extreme values of ladder slamming pressure are predicted, providing a reference for the structural design of next-generation large self-propelled cutter suction dredgers.