Developing high-efficiency and low-cost photocatalysts by avoiding expensive noble metals is a great challenge. Here, highly dispersed metal (M = Ni, Co, Fe) phosphides modified g-C3N4 nanosheets (CNNS) were prepared through in situ precipitation and solid/gas-phase phosphorization. The results confirmed that metal phosphides (MPX) nanoparticles with high dispersion were well loaded on CNNS surface. The property well reveals the transfer path of photogenerated charges and the origin of high charge separation efficiency in photocatalytic reaction, thus yielding a remarkable catalytic activity. The apparent quantum efficiency (AQY) based on the NiPx/CNNS-900 is up to 6.61% at 400 nm while the H-2 evolution rate boosts to 4068.84 mu mol.g(-1).h(-1), which is 50 times higher than that of pristine CNNS. The mechanism could be attributed to the highly dispersed MPX nanoparticles on the surface of CNNS, which acted as effective active sites to promote the separation and migration of photogenerated charges, leading to greatly increase in H-2 production. This study is beneficial to further develop the high-efficient, low cost and environmentally-friendly CNNS-based photocatalytic materials for H-2 production.