Physical Downlink Control Channel (PDCCH) is used to signal dynamic resource assignment information in Long Term Evolution (LTE) system. In the presence of numerous active UEs, their control channel resource location based on PDCCH blind decoding mechanism is determined by the Radio Network Temporary Identifier (RNTI) which is allocated to UEs by eNodeB when they first access to the cell. Choosing RNTI properly can improve UEs' system performance. In this paper, we proposed three RNTI allocation schemes: RNTI continuous allocation scheme, RNTI table allocation scheme and RNTI random allocation scheme. We also developed two simulation models to evaluate our RNTI allocation schemes. The simulation results prove that RNTI table allocation scheme is better than other two allocation schemes both in eliminating conflict probability and increasing CCE utilization ratio.