Elastic Optical Networks (EONs) are considered as very promising architectures for future optical transport networks, since they efficiently use the spectrum resources and provide high bandwidth scalability and granularity. In this paper, the multicast routing problem in EON is considered. A fragmentation-aware multicast routing algorithm, named as Weighted Dynamic Fragmentation-aware Multicast Routing Algorithm (W- DFMRA), is proposed to solve this problem. Simulations show that the fragmentation and blocking ratio of the proposed algorithm can achieve good results.