Control and insight into the abundance of inter-shelled channel active sites and charge transport mechanism are the long-term challenges for enhancing photocatalytic activity. Herein, the Ni2P quantum dots (QDs) are decorated in the multi-shelled CaTiO3 cube for creating the abundance of inter-shelled channel active sites, which greatly improve the photocatalytic performances for generating H2 and degrading tetracycline (TC) relative to pure CaTiO3 and Ni2P. Moreover, the Z-scheme mechanism and the quantum effect of the Ni2P in multi-shelled CaTiO3 cube play a crucial role for enhancing photocatalytic performance. Furthermore, the photoelectric researches demonstrate that the Ni2P/CaTiO3 heterostructure possesses more abundant active sites, smaller interface transmission resistance and faster photo-generated charge transfer efficiency. This work provides a meaningful model to research other materials with creating the abundance of inter-shelled channel active sites for the photo-electrocatalytic field.