In order to demonstrate the superiority of using MgO-mixed concrete in dam construction, autoclave tests of cement-fly ash-stone dust mixed paste specimens were conducted according to the autoclave principle, and the mixing ratio of MgO in the specimens was increased to 6. 5%. This technology was applied to the concrete arch dam of a grade IV small-scale(type 1)hydropower station. The results show that concrete with a high content of MgO can improve the anti-cracking performance of the dam concrete and simplify temperature control measurements of mass concrete, allowing for an improved concrete dam construction method, in which few induced joints are needed, longitudinal joints can be cancelled, and entire concrete blocks of the dam body can be poured.