Abstract: A mixture algorithm is used to perform ship route planning and smoothing for complex navigation waters. The algorithm is basically the Improved Ant Colony Algorithm with introduction of the bidirectional search algorithm to avoid being trapped in local optima. The turning angle function ω is introduced to smooth the generated route, so as to reduce the number of turning points. Bidirectional A star algorithm is used to improve the directivity in the search process. Pheromone evaporation coefficient ρ is improved according to the relevance of the number of iterations to pheromone retention. Experiments show that the method developed here converges faster than typical ant colony optimization and bidirectional ant colony optimization and generates smoother route, the number of turning points is 46% less for average navigation environment and 53% for complex navigation environment.