To　address　significant　disturbances,　including　sudden　air　flow　variation,　model　uncertainty,　and　unavoidable　measurement　noises　during　aeroengine　transient　tests　in　the　intake　environmental　pressure　simulation　system　(IEPSS),　a　sliding　mode　active　disturbance　rejection　controller　(SMADRC)　is　designed.　The　sliding　mode　control　in　SMADRC　can　deal　with　unmatched　disturbances　that　are　beyond　the　capabilities　of　the　extended　state　observer　(ESO)　in　ADRC.　And　the　particle　swarm　optimization　(PSO)　algorithm　is　introduced　to　tune　and　optimize　the　controller　parameters　to　further　enhance　the　performance.　To　validate　the　effectiveness　of　the　proposed　method,　simulations　are　conducted　on　the　IEPSS　software　platform.　The　simulation　results　clearly　demonstrate　PSO-SMADRC　can　reduce　the　mean　squared　error　by　60.9%,　the　input　oscillation　by　68.7%,　and　the　maximum　deviation　by　53.9%,　compared　with　LADRC　originally　applied　in　the　IEPSS.