In the business of logistics distribution, the key is cost optimization which could reduce cost and increase economic returns. According to the character of logistics distribution, the model of cost optimization was set up .The model separated the cargo for one customer into common cargo and urgent cargo , which offered a new idea to reduce distribution cost under the conditions of crash time and the transportation capacity limited. On the basis of this model, the cost optimization genetic algorithm was created and is a specific method and process to apply the algorithm . Actual example shows that the method can get convergence to an outstanding solution fast and efficiently.Therefore this method can get better optimization result during cost optimization of logistics distribution.