Coastal ports are the transportation field with the highest degree of marketization in China，and the port capacity level is closely related to the operation of the market economy.At present，the actual cargo throughput of some berths in coastal ports far exceeds the statistical value of berth passing capacity，presenting the phenomenon of “overload” operation.It reflects the inadaptability of the existing statistical method of berth capacity.It is also worth noting whether the “overload” operation would bring production safety problems.Given the requirements of ensuring the stability and safety of the shipping supply chain of important strategic materials，supporting the construction of strategic reserve bases for bulk cargoes，and improving the emergency deployment capacity of civilian materials，this paper combs through the normative design algorithms and current statistical rules for berth passing capacity in detail.Regarding the “overload” operation phenomenon of berths，this study mainly analyzes the reasons for the statistical distortion of berth passing capacity and suggests using the “berth utilization rate” index to characterize the berth capacity.The research provides a technical reference for reasonably understanding and judging the wharf passing capacity，grasping the real-time development and real dynamics of coastal ports in China，and realizing reasonable decision-making and scientific management.