This paper introduces an optimization model ( COSDM) of Container Ocean-transportation System with the objective of maximizing the profit of a liner company，while taking the seasonal changes of transporta-tion demands and choice inertia of shippers into consideration． COSDM can optimize shipping network design and fleet deployment simultaneously． It also optimizes the plans for shipping network adjustment and for dis-trusting slots in ships based on the fluctuant demand and the characteristics of the shippers’chosen inertia． To solve COSDM，a heuristic algorithm ( ACOSP) is put forward by combining Genetic Algorithm and Linear Pro-gramming． The experimental results show that COSDM can give an optimized design of the system in consider-ation of the stability of transporting services． The proposed model also improves the user experiences of the shippers while increasing the profit of the liner company．