The　rise　of　Internet　of　Things　applications　and　the　limitations　of　the　cloud　computing　promote　a　new　distributed　computing　model　called　fog　computing,　processing　data　at　the　edge　of　the　network.　Fog　computing　introduces　an　intermediate　layer　between　user　equipment　and　cloud,　which　complements　cloud　computing　with　low　latency　services　for　UE.　In　this　paper,　the　optimization　between　transmission　delay　and　processing　delay　in　the　fog　computing　access　system　is　investigated.　We　model　the　fog　access　system　with　3-layer　model　and　propose　an　access　optimization　algorithm　based　on　the　model.　Simulation　results　show　the　correctness　of　the　analysis　and　the　performance　improvement　of　the　proposed　strategies　in　the　fog　computing　access　networks.　©　2017　IEEE.