The 3rd generation partnership project (3GPP) has defined two communication modes of centralized (mode 3) and distributed (mode 4) for long term evolution-vehicle to everything (LTE-V2X). Mode 4 supports direct-connected communication, and adopts the semi-persistent scheduling (SPS) resource allocation scheme based on awareness, and the vehicle selects the best sub-channel through awareness. In order to solve the uncertainty of resource selection and low resource utilization of SPS algorithm in mode 4, a resource pre-selection scheme was proposed to determine the location of pre-selected resources in advance, and adjust the size of the sensing window and the weighting method of the received power intensity of the reference signal according to the degree of channel congestion during the sensing process, so as to reduce the probability of resource collision and improve the reliability of transmission. The simulation results show that compared with the SPS mechanism in the standard, the proposed resource allocation scheme can effectively improve the packet reception ratio, reduce the communication delay and meet the goal of high reliability and low delay of the Internet of Vehicles (IoV) in the high traffic density scenario.