Clay　attached　in　concrete　has　deterioration　effect　on　the　application　of　high-performance　concrete.　In　this　paper,　the　improvement　of　polycarboxylate　superplasticizer　(PCE)　synthesized　based　on　the　molecular　calculation　on　the　negative　effect　of　clay　was　investigated,　and　the　mechanism　was　revealed　by　adsorption,　thermal　gravimetric　(TG)　and　X-ray　diffraction　(XRD)　measurements.　The　adsorbed　substance　between　interlayers　of　clay　was　side　chains　rather　than　the　whole　PCE,　and　thus　a　spatial　PCE　with　large　dimension　was　synthesized　followed　by　1H　nuclear　magnetic　resonance　(1H　NMR)　and　gel　permeation　chromatography　(GPC)　characterizations.　The　results　showed　that　in　existence　of　clay,　the　fluidities　of　cement　pastes　containing　this　PCE　increased　by　22.2%-35.7%,　but　also　for　the　1　h　slump　of　concrete.　This　is　ascribed　to　its　large-sized　structure　which　can　generate　steric　hindrance　effect,　and　thus　its　side　chains　can　be　prevented　from　being　adsorbed　in　between　interlayers　of　clay　to　ensure　good　dispersing　effectiveness,　presenting　an　inhibition　of　negative　effect　of　clay.　©　2018,　Materials　Review　Magazine.　All　right　reserved.