With China's rapid economic development, electricity supply is relatively shortage, and the contradiction of power coal supply and demand is prominent. In this context, using WITNESS logistics software platforms, this paper establishes a simulation model about a power coal ocean shipping logistics system of a transshipment port as the center, focusing on how to make full use of the existing resources of a transshipment port for studying transshipment port operating mechanism through the running simulation model and optimal design of power coal logistics cost in order to guarantee security and stability of power coal-fired supply and maximize logistics system economic benefits. Keywords Transshipment Port, WITNESS, Power Coal and Ocean Shipping Logistics System.