Abstract: Various design methods are available in China for ultra-high fly ash content hydraulic concrete, but the fly ash volume content in normal hydraulic concrete could hardly exceed 50% due to the restrictions of their design concept and methodology and the existing regulations, showing a significant difference from the current techniques overseas. This paper describes a new design method of mixing fly ash and ordinary portland cement that can raise the mix portion of fly ash up to 80% and retain all the performances meeting the requirement of hydraulic concrete C18040. Compared with the concrete with the same strength grade but a lower content 35% fly ash mixed with medium heat cement by the common method, this new design is superior in lower hydration temperature rise, less shrinkage, and lower total cost. Thus, it would provide a new method to demonstrate the integrated meanings and real characteristics of hydraulic concrete.