The service life of concrete structures shortened by corrosive ions endangers public safety and results in considerable repair costs worldwide. For the objective of producing more sustainable concrete, how do polycarboxylate superplasticizers (PCEs) with different side-chain lengths affect the resistance of concrete to chloride penetration and sulfate attack is studied. The foam and adsorption behavior of PCEs, the heat release of cement hydration, the resistance of concrete to chloride penetration and sulfate attack and the microstructure observation were investigated to achieve the aim. Results show that the shortest side-chain PCE (M400C3.5, nEO = 9) had the best effect on improving the resistance of concrete to chloride penetration and sulfate attack. Among all the tested concrete samples, the concrete containing M400C3.5 exhibited the lowest total porosity and the most compact structure. The largest adsorption amount of M400C3.5 on the cement surface led to the most significant retardation of the initial cement hydration. This retardation may reduce the number of microcracks resulting from fast heat release.