Strategic　petroleum　reserve　(SPR)　plays　an　vital　role　in　ensuring　energy　security.　China　initiated　the　strategic　petroleum　reserve　in　2004.　The　optimal　scale　of　SPR　has　become　a　concern　to　policymakers.　The　paper　adopts　a　computable　general　equilibrium　(CGE)　model　to　examine　the　influence　of　oil　shortages　on　the　economy.　It　is　revealed　that　when　the　shortage　rate　reaches　25%,　the　price　of　domestic　crude　oil　will　rise　by　121.2%,　the　price　of　refined　petroleum　products　will　rise　by　67.8%,　and　the　GDP　will　decline　by　0.7%.　The　GDP　loss　is　accelerated　with　the　shortage　rate　rises.　The　output　of　coal,　electricity　and　other　energy　will　increase,　and　most　non-energy　sectors　will　decline.　There　is　an　inverse　U-shaped　curve　between　net　export　and　oil　shortage.　Based　on　the　result　of　CGE,　we　further　develop　a　framework　to　determine　the　optimal　SPR.　The　results　indicate　that　the　optimal　stockpile　is　389　million　barrels,　which　is　higher　than　the　current　reserve　scale.　At　least　an　additional　198　million　barrels　of　reserves　are　required.　In　addition,　a　sensitivity　analysis　is　conducted　to　quantify　the　impact　of　exogenous　variables.　The　findings　of　this　paper　can　provide　reference　information　for　the　policy　maker　to　formulate　SPR　planning.　©　2022　The　Author(s)