This paper focuses on the resource allocation of multicast services in Distributed Antenna Systems (DAS). First of all, the capacity limitation of conventional multicast ransmission in DAS is analyzed. Then a resource allocation algorithm for multicast services is proposed to improve the system throughput of DAS with Quality of Services (QoS) guarantees. The proposed algorithm includes three steps: Power Assignment, Conservative Allocation and Greedy Step. Simulation results show that the proposed algorithm significantly outperforms the conventional multicast transmission methods in throughput while guaranteeing the minimum data rates of all users as well. Moreover, simulation results also show that the proposed algorithm can exceed the capacity upper bound of conventional multicast scheme when the user number is larger than 50, which indicates the proposed algorithm can overcome the capacity limitation of conventional multicast transmission in DAS.