The early-age rheological properties of hydraulic engineered cementitious composites (HECC) were investigated through rheological tests, workability tests, setting time tests, and hydration heat tests. The effects of three superplasticizers, a high-performance polycarboxylate superplasticizer (PCA-1), a non-slump-retaining high-performance polycarboxylate superplasticizer (PCA-2), and an early-strength high-performance polycarboxylate superplasticizer (PCA-3), on the rheological characteristics of HECC were evaluated. The results showed that the rheological behavior of fresh HECC followed the Bingham model, with both yield stress and viscosity increasing over time. At the same dosage, the three superplasticizers exhibited similar water-reducing effects but differed in slump retention. At a given testing time, mixtures containing PCA-3 exhibited slightly higher yield stress and viscosity. The initial and final setting times determined by the penetration resistance method were 3-4 h and 5-6 h longer, respectively, than those determined by the Vicat method. Field construction observations confirmed that the penetration resistance method provided more accurate results. The heat release peaks of mixtures containing PCA-2 and PCA-3 occurred 1.93 h and 1.77 h earlier, respectively. Cumulative heat release decreased by 1.366 J/g with PCA-2 and increased by 0.998 J/g with PCA-3. The early-strength superplasticizer regulated the rheological characteristics of HECC by promoting hydration, whereas the non-slump-retaining superplasticizer exerted its effect by affecting interparticle adsorption.