Three kinds of comb-like polycarboxylate superplasticizers (PCEs): polycarboxylate superplasticizer with long side chain(LPCE), polycarboxylate superplasticizers with long and short side chain (LSPCEs) and polycarboxylate superplasticizer with short side chain (SPCE) were synthesized by free polymerization in aqueous solution with ammonium persulfate (APS) as initiator and sodium methacrylate sulfonate (MAS) as chain transfer agent. The effect of the ratio of long and short side chains on the early hydration behavior of cement was studied, and the mechanism was further discussed through the research of the aggregation morphology, adsorption performance and air entrainment performance of PCEs aqueous solution. The results show that SPCE is helpful to delay the early hydration of cement and increase the hydration induction period. This is because SPCE contains more carboxylic acid radicals than LSPCEs and LPCE. The adsorption amount of SPCE on the surface of cement particles is the largest and the thickness of the adsorption layer is the highest. After adding cement, the foaming height of PCEs aqueous solution tends to increase with the increase of short side chain ratio, but the viscosity of LPCE aqueous solution is higher, and the foam stabilization performance is better than that of LSPCEs and SPCE.