Disclosed is a preparation method for a nickel-cobalt-manganese raw material with ion co-equilibrium in hydrometallurgy of laterite nickel ore, including the following steps: acquiring parameters of an initial material liquid, an actual pH of a material liquid at a reaction endpoint, and a target precipitation rate of a target metal; establishing a first theoretical relationship model between a theoretical pH of the material liquid at the reaction endpoint and the target precipitation rate of the target metal, and obtaining the theoretical pH of the material liquid at the reaction endpoint based on the parameters of the initial material liquid and the first theoretical relationship model; and judging whether to terminate the reaction based on the theoretical pH and the actual pH of the material liquid at the reaction endpoint. The present application guides the MHP precipitation process from the perspective of ionic balance. Through the method of the present application, the theoretical pH of the material liquid at the reaction endpoint can be directly obtained based on the parameters of the initial material liquid and the target precipitation rate of the target metal, thus judging whether to terminate the reaction through the theoretical pH of the material liquid at the reaction endpoint and the actual pH of the material liquid at the reaction endpoint.