Molasses is a by-product of sugar industry which is used as a water reducing admixture in concrete. The positive effects of fly ash as a partial replacement of cement on the strength and durability of concrete are recognized through various researches. This paper deals with the comparisons of the deflection and equivalent stress of the RCC beams in which cement is replaced by fly ash with 30% and sugar molasses as an admixture with 0.15% and without sugar molasses for various range of loads using Ansys software. The size of the beam is taken as 150x200x1000mm and it can be concluded that there is 11% of reduction in deflection and 7% decrease in equivalent stress in the RCC beam which contain sugar molasses