Recently,　electric　vehicles　(EVs)　have　been　widely　used　under　the　call　of　green　travel　and　environmental　protection,　and　diverse　requirements　for　charging　are　also　increasing　gradually.　In　order　to　ensure　the　authenticity　and　privacy　of　charging　information　interaction,　blockchain　technology　is　proposed　and　applied　in　charging　station　billing　systems.　However,　there　are　some　issues　in　blockchain　itself,　including　lower　computing　efficiency　of　the　nodes　and　higher　energy　consumption　in　the　consensus　process.　To　handle　the　above　issues,　in　this　paper,　combining　blockchain　and　mobile　edge　computing　(MEC),　we　develop　a　reliable　billing　data　transmission　scheme　to　improve　the　computing　capacity　of　nodes　and　reduce　the　energy　consumption　of　the　consensus　process.　By　jointly　optimizing　the　primary　and　replica　nodes　offloading　decisions,　block　size　and　block　interval,　the　transaction　throughput　of　the　blockchain　system　is　maximized,　as　well　as　the　latency　and　energy　consumption　of　the　system　are　minimized　Moreover,　we　formulate　the　joint　optimization　problem　as　a　Markov　decision　process　(MDP).　To　tackle　the　dynamic　and　continuity　of　the　system　state,　the　reinforcement　learning　(RL)　is　introduced　to　solve　the　MDP　problem.　Finally,　simulation　results　demonstrate　that　the　performance　improvement　of　the　proposed　scheme　through　comparison　with　other　existing　schemes.