In this paper, the hydration process of cement paste with hydrophilic nano-TiO2 particles was studied by microcalorimeter and electrochemical impedance spectroscopy, and the hydration mechanism was explored based on Krstulovic-Dabic kinetic model. Meanwhile, the photocatalytic activity and antibacterial properties of TiO2-modified cement pastes were investigated by ultraviolet spectrophotometer and enzyme activity analyzer respectively. The results show that TiO2 nanoparticles can promote the hydration rate of cement in the acceleration stage, increase the cumulative heat release of early hydration, but delay the hydration process in the later stage. The Krstulovic-Dabic model can effectively simulate the hydration process of cement pastes with TiO2. Nano-TiO2 helps to increase the hydration rate of the crystal nucleation and growth process (NG) and shorten the duration of phase boundary reaction process (I), but has a negative impact on ion diffusion process (D). The functional relationship between the resistivity ρ of TiO2 cement-based composites and the hydration kinetic parameters was established: ρ(t)=−1k1ln[β1+t50t−t0].The degree of hydration of cement can be assessed by electrochemical in-situ non-destructive monitoring of the sample. In addition, the photocatalytic oxidation rate of TiO2-modified cement-based composites was up to 69.4%. Compared with the control sample without nano TiO2, the antibacterial ability was increased by 72.35%. In this paper, nano-TiO2 was applied to cement system, which provided a new idea for the preparation and application of photocatalytic antibacterial cement-based composites.