Efficient spectrum resource allocation in wireless heterogeneous networks is important for improving the system throughput and guaranteeing the user’s Quality-of-Service(QoS).In this paper,we propose an enhanced algorithm for spectrum resource allocation in heterogeneous networks.First,the bandwidth of each user is determined by the user’s rate demand and the channel state.Second,graph theory is enhanced and used to improve the spectrum efficiency.Third,spectrum resource is dynamically split between macrocell and femtocells with the changes of users’ conditions.Our simulation results show that the proposed algorithm improves the system throughput significantly and also guarantees the fairness for the users. Efficient spectrum resource allocation in wireless heterogeneous networks is important for improving the system throughput and guaranteeing the user’s Quality-of-Service (QoS) .In this paper, we propose an enhanced algorithm for spectrum resource allocation in heterogeneous networks. First, the bandwidth of each user is determined by the user’s rate demand and the channel state .Second, graph theory is enhanced and used to improve the spectrum efficiency.Third, spectrum resource is dynamically split between macrocell and femtocells with the changes of users’ conditions.Our simulation results show that the proposed algorithm improves the system throughput significantly also also the fairness for the users