The filter mud in molasses has a significant inhibitory effect on biological activity and cannot be utilised by organisms; therefore, before molasses are biotransformed, the filter mud will be separated and directly discarded in the environment. In this study, the filter mud was used as the retarder of cement concrete OPC 42.5 for the first time. It was found that when 0.2–0.8% filter mud was added to fresh cement concrete OPC PC 42.5, the hardening time of cement slurry was significantly prolonged due to the synergistic retarding effect of sugar, colloid and total cellulose in the filter mud. In addition, the compressive strength of cement concrete mixed with the filter mud in the early stage (<10 days), middle stage (10–100 days) and later stage (180 days) was significantly higher than that of cement concrete and cement concrete mixed with commercial asphalt lignosulfonate. These results showed that the filter mud in molasses could realise harmless and resource utilisation, which could promote the comprehensive utilisation of molasses.