Different　configurations　and　proportion　of　phase　change　material　(PCM)　have　a　vital　impact　on　the　thermal　performance　of　the　battery　thermal　management　system　(BTMS).　In　this　work,　the　thermal　performance　of　the　battery　pack　is　investigated　by　a　combined　PCM　and　air　cooling　technique.　Firstly,　four　cases　of　PCM　configuration　are　proposed　to　investigate　the　heat　dissipation　performance.　Then　PCM　proportion　is　optimized　to　obtain　better　temperature　uniformity,　smaller　energy　loss　and　smaller　amount　of　PCM　based　on　Case　4.　Finally,　subjected　to　the　installation　space　constraint　of　battery　box　(smaller　volume),　Case　5　is　designed　to　diminish　the　volume　of　battery　box　and　the　corresponding　thermal　performance　is　discussed.　The　results　show　that　thermal　performance　with　PCM　is　superior　than　that　without　PCM;　Case　4　not　only　enhances　the　thermal　performance　but　also　reduces　the　amount　of　PCM;　The　optimized　PCM　proportion　is　only　64　%;　Compared　with　all　PCM,　the　optimized　Delta　T,　Delta　P　and　PCM　volume　respectively　reduce　11.91　%　(0.83　K),　11.61　%　(4.18　Pa)　and　43.06　%　(215,544　mm3);　Case　5　not　only　shows　more　better　thermal　performance　than　Case　4　but　also　reduces　102,200　mm3　(3.48　%)　volume　of　the　battery　box.　The　proposed　strategy　is　effective　for　improving　thermal　performance　of　BTMS　and　saving　the　amount　of　PCM.