The purpose of this study was to evaluate the engineering properties of the high-flowing fine-grained concrete (HFFC) developed using various components such as cement, slag, fly ash (FA), natural crushed sand, crushed stone, water, and superplasticizer (SP). Six HFFC mixture proportions were prepared in the laboratory, in which three mixtures got a variety of water-to-binder (w/b) ratio in the range of 0.32–0.42 while the other three mixtures were setup from selected w/b ratio of 0.37 and the substitution of Portland cement by slag at 0 (reference), 10, 20, and 30% by mass of cement. Engineering properties of all HFFC specimens were evaluated through the tests of compressive strength, flexural strength, water absorption, porosity, drying shrinkage, and sulfate resistance. Additionally, the properties of fresh HFFC mixtures, including workability and unit weight, were measured. Test results showed that the cement replacement by slag significantly improved compressive and flexural strengths, and reduced water absorption and porosity of the HFFC samples when compared with the reference sample. Moreover, the use of slag to partially replace cement was found to enhance sulfate resistance and reduce drying shrinkage of the HFFC samples. This study found that using slag could improve the engineering properties of HFFC for hydraulic structures.