Ultra dense networks are a promising technology enabling high power and spectrum efficiencies in future wireless systems. It is well-known that for ultra dense networks inter-cell interference is one of the main bottlenecks prohibiting achieving the promised performance gains. In order to effectively coordinate or mitigate interference in paper, we propose a graph-based low complexity dynamic clustering algorithm. The key idea behind the proposed algorithm is that dividing the whole network into a number of clusters under size constraint and the maximum intra-cluster interference and minimum inter-cluster interference. The logic is maximum intra-cluster can be effectively controlled by the coordination within each cluster. Meanwhile, graph-based algorithm is exploited to further reduce implementation complexity and make the proposed algorithm suitable for practical implementation. Finally, simulation results numerically demonstrate that the proposed low complexity algorithm has almost the same performance compared to the existing high performance algorithm but the complexity is much lower.