Cow dung is a waste substance which is excreta of cows, which was used by our ancestors for floor and wall finishing by mixing it with soil. The dried cow dung is used as manure in cultivated land. The dried cow dung was also used as fuel for cooking food and boiling water which was obtained by drying the cow dung in open air for few days. The refuse left after burning is termed as Cow Dung Ash (CDA). CDA is a multipurpose material, as in rural areas it is also utilized as cleaner while washing the utensils. This ash is a waste substance and mostly used in fields as a filler material to elevate or to level the land and also used for soil stabilization by the farmers in marshy areas. CDA has shown pozzolanic traits, hence can be used in replacement to cement partially in making sustainable green concrete. In this study, the cement of M30 Grade concrete is replaced in weight percentage like 10%,15% & 20% and experiments were performed to compare the results with normal conventional concrete. For mechanical properties, compressive strength test, flexural strength test and split tensile strength test were performed over CDA modified concrete specimen. Material characterization of CDA using X-Ray fluorescence (XRF) test has been done to know the different elements and compounds present in CDA. After examining the mechanical properties of CDA modified concrete, 10% is the optimum value of CDA in replacement to cement without compromising strength parameters of the normal concrete (NC).