For photocatalysis, clarifications of charge carrier migration route and kinetics on individual particles by photoluminescence (PL) are of great importance because they play significant roles on unveiling the precise information of structure-activity relationships and closely relate to the photocatalytic activities of those semiconductors on targeted functions. Here, photodeposition process of NiS nanoparticles on single TiO2 mesocrystal (TMC) as co-catalyst is in situ monitored by PL images and spectra using a confocal single-particle PL microscopy, which provides straightforward results on understanding the photoexcited electrons transfer in both individual TMC and TMC/NiS nanoparticles. Through the changes in PL intensity and decay lifetime, preferential trapping site for NiS nanoparticles on TMC is identified and efficient electron interfacial migration from TMC to NiS nanoparticles is demonstrated, which lead to an almost 71 folds enhancement on the photocatalytic H-2 evolution under 365-nm photoirradiation compared to pure TMC particles.