Abstract: Decision Support System is developing from its starting as a support tool and it is becoming the common resource in an organization. Decision Support System serve the management level of an organization for support to make decisions. Data Mining and DSS can lead to the improved performance and can enable to handle new types of problems. Classification is main task of Data Mining, various types of classification algorithms have been proposed and compared to determine the trends on data. There has been no single algorithm are to be superior over all others for data sets. Robustness and scalability must be considered for judging the suitable algorithm for any data, In this paper two decision tree algorithm, one algorithm are tested and compared.