Due　to　the　rocketing　development　of　the　Internet　of　Vehicles　(IoV),　the　growth　of　computing-intensive　and　latency-sensitive　applications　brings　a　challenge　to　individual　vehicles　with　limited　computing　resources.　The　computation　offloading　technology　provides　a　feasible　solution　to　this　issue.　In　this　paper,　a　multi-tier　symmetric　Vehicle-to-Everything　(V2X)　network　framework　is　proposed,　which　consists　of　vehicle　nodes　(VNs),　mobile　edge　computing　(MEC)　servers　and　a　cloud　server　to　provide　computation　offloading　services　for　user　vehicles.　In　this　symmetric　system,　besides　local　computation,　tasks　can　be　offloaded　to　VNs　or　MEC　servers　or　cloud　servers　for　processing.　The　computation　offloading　problem　in　this　network　framework　is　considered　as　a　game　based　on　game　theory.　Then,　in　order　to　achieve　the　Nash　equilibrium　(NE)　in　this　game,　a　joint　optimization　of　computation　offloading　and　resource　allocation　(JOCORA)　algorithm　is　proposed.　The　numerical　simulations　show　that　the　JOCORA　algorithm　can　improve　the　success　probability　of　offloading　and　reduce　the　total　latency.　The　JOCORA　algorithm　has　a　better　performance　compared　to　other　methods.