Ultra Dense Network will undoubtedly play an important role in next generation communication network due to its excellent system performance. However, the deployment of large-scale small cells can cause serious interference problems among users. Therefore, this paper proposes an interference vector judgement based user clustering scheme to suppress the system throughput degradation problem caused by interference. For our proposed scheme, it first gives a design of inter-user interference weight to obtain user interference vectors; secondly, users are clustered by adjudicating the relative interference values between user interference vectors. In simulation, it can demonstrate that our proposed algorithm achieves significant improvements in enhancing system throughput, especially for cell-edge users, by comparing it with some other existing algorithms.