In　recent　years,　panoramic　video　has　gradually　emerged　in　the　multimedia　industry.　As　an　important　part　of　the　panoramic　video　processing　process,　the　choice　of　projection　mapping　method　will　affect　the　efficiency　of　panoramic　video　coding　and　decoding,　transmission　mode　and　user　experience.　There　have　been　a　lot　of　researches　on　the　projection　method　from　the　spherical　surface　to　the　plane,　and　its　important　purpose　is　to　reduce　the　distortion　of　the　spherical　video　in　the　projection　and　improve　the　performance　of　panoramic　video　encoding.　At　present,　projection　methods　are　mainly　divided　into　uniform　quality　projection　and　non-uniform　quality　projection.　This　paper　compares　several　common　projection　mapping　methods,　discusses　their　respective　advantages　and　disadvantages,　and　makes　related　summary　at　last.　©　2021　IEEE.