Transition metal phosphides (TMPs) have attracted attention in electrocatalytic hydrogen production because of their multiple active sites, adjustable structures, complex and variable composition, and distinctive electronic structures. However, the catalytic performance of pure TMPs in the hydrogen evolution reaction (HER) is not ideal. Fortunately, this situation can be changed by atom doping engineering because atom doping can efficaciously adjust the electronic structure, Gibbs free energy (ΔG_H*) and d-band center to enhance the kinetics of catalytic reactions. Thus, atom doping engineering has aroused widespread interest. This review examines, analyzes and summarizes our previous work and that of others on atom doping engineering, including the activity origin of doped TMPs, doping with nonmetals (B, S, N, O, F, etc.), doping with metals (Ni, Co, Fe, Mn, Mo, Al, etc.) and codoping with nonmetals and metal atoms, as well as direct doping and synergetic doping, doping methods and the resulting HER properties. Finally, the key problems and future directions for development of atom doping in TMPs are discussed. This review will aid the design and construction of high-performance nonnoble metal catalysts for the HER and other electrocatalytic processes.