With the rapid development of vehicular access network, three different communication modes have emerged as the fundamental technologies in cellular V2X, i.e., cellular mode, reuse mode, and dedicated mode, through different spectrum sharing strategies. However, how to conduct the multi-mode access management for cellular V2X is challenging considering the heterogeneity of network resource and the diverse vehicular services demands. In this paper, we investigate a software defined multi-mode access management framework in cellular V2X, which is capable of providing flexibility and programmability for dynamic spectrum sharing in vehicular access. We first conduct the performance analysis of multi-mode communications in cellular V2X. Then, we design an analytic hierarchy process (AHP) based evolutionary game to optimize the multi-mode access management solution, in which four performance indicators are jointly considered, including transmission rate, interference, transmission delay, and energy consumption. Extensive experimental simulations have validated the superiority of the proposed algorithm, and illustrated the impact of different vehicle access schemes, signal-to-interference-plus-noise ratio (SINR) threshold and other parameters on the performance of cellular V2X. © 2021, Posts and Telecom Press Co Ltd. All rights reserved.