In this paper, it is considered that chaos synchronization of Chen fractional order time-delay chaotic systems and its application in secure communication. By use of the fractional calculus techniques, the authors find that chaos exists in the fractional order Chen system with time delays when the order is less than 3. Firstly, based on the Laplace transform theory, the conditions for achieving synchronization of different fractional order time-delay chaotic systems are analyzed. Then the proposed method is applied to secure communications. At last, numerical simulations are provided to verify the effectiveness and feasibility of the developed method.