Rainfall is a one of the important phenomena of the hydrological cycle; its distribution time to time, varies from one place to another place; and it acts as a source of water to the earth. Indian agriculture and the cropping pattern, with good yield of production, depend on the rainfall during monsoon. According to the IMD, South peninsular region got 40% of rainfall from South-West monsoon and 60% from North-East monsoon. This study aims at understanding the spatial distribution of rainfall and its influences in the hydrological trend of precipitation over the area which is closely linked with flood and drought. For the purpose of evaluation, the rainfall data of 21 stations were collected from statistical department and PWD Ground water division of Cuddalore district during period of 1986 – 2016. After error correction and checking, the general methodology was applied for this study. The collected data and the real time data were matched for the mathematical analysis to find the Mean, Seasonal variation, Coefficient of Variation, Precipitation Ratio. The spatial distribution of rainfall convert as the non spatial data of an attribuutive information in the form of statistics, tabled list, graphs and finally, using the ILWIS software, to find the influence of rainfall over the area were identified and demarcated with maps. The long term rainfall analysis identifies the influence and pattern of spatial distribution of Cuddalore district.