This paper develops a novel scheme of adaptive user association strategy by integrating cell range expansion (CRE) and enhanced inter-cell interference coordination (eICIC) for LTE-A heterogeneous networks (HetNets). Particularly, we take advantage of the adaptive CRE bias to balance the traffic between the macro cell and the low-power nodes (LPNs). Our work addresses the issues of adaptive scheme, which associates appropriate CRE bias to dynamically expand the coverage of the LPNs. We further develop a adjustable function to calculate the CRE bias based on the current user distribution. Simulation results justify that our approach can significantly improve the balance between the macro cell and the LPNs as well as guarantee the system throughput.