The invention relates to a concrete bleeding inhibitor. The concrete bleeding inhibitor comprises the following raw material components in parts by weight: 0 to 20 parts of a macromonomer, 0 to 20 parts of a micromonomer, 0.2 to 5 parts of an oxidizing agent, 0.005 to 2 parts of a reducing agent, and an antioxidant with the addition amount being 0.001 to 0.05%of the total weight of the macromonomer, the micromonomer, the oxidizing agent and the reducing agent. The concrete bleeding inhibitor provided by the invention can well inhibit bleeding and hysteretic bleeding of concrete, improves the workability of concrete, and effectively improves the stability of later-period mechanical properties and the use durability of the concrete. A preparation method for the concrete bleeding inhibitor comprises operation steps like mixing, heat-preserving, and standing/stirring, has simple operation process, does not involve high-temperature and high-pressure operations in the process of production, has safe production process and low cost, and is applicable to scale production.