The effects of nano-C-S-H/PCE on the setting time, early hydration and compressive strength of Portland-Sulphoaluminate composite cement were studied. The early-age hydration products were analyzed by XRD, TG, pH meter and SEM. The hydration products and liquid alkalinity were characterized. The enhancement mechanism of nano-C-S-H/PCE on Portland-Sulphoaluminate composite cement was studied. The results showed that the addition of nano-C-S-H/PCE could effectively shorten both the initial setting time and final setting time of fresh composite cement paste. When the C-S-H/PCE content was more than 1.0%, the initial time difference of the composite cement was obviously shortened. The nano-C-S-H/PCE accelerated the hydration heat releasing rate of the composite cement, and increased the total hydration heat. The hydration products were increased obviously, however, it had no effect on the type of cement hydration products. The compressive strength of the composite cement mortars at 8h, 12h and 16h were significantly increased.