As one of the core technologies of future autonomous vehicles,Cellular-V2X(C-V2X) faces a series of developing pain points related to network connectivity,such as mobility,coverage and spectrum,while rapidly popularizing its application.The connectivity of C-V2X based cooperative vehicle-infrastructure system directly reflects the overall performance of C-V2X network connected vehicles,which is of great significance to ensure information can achieve long-distance,adaptive,low latency and high reliable transmission.Different from the traditional cellular mobile communication network,C-V2X networking vehicles have the characteristics of high moving speed,short link duration between nodes,strong predictability of wireless communication environment,and mobility model limited by road topology.To make efficient use of spectrum for communication,C-V2X networking vehicles also have the characteristics of no center and self-organization of ad hoc network.Firstly,the advantages and characteristics of C-V2X are briefly introduced,including the progress and structure of C-V2X.On this basis,research on connectivity of C-V2X network are summarized and classified based on transportation scenarios,communication mode selection,road side unit(RSU) location deployment,power control and model driven.Finally,the development trends of connectivity for C-V2X are discussed and its future application is prospected.