 Abstract: Security is the critical part in the computers and the networks which connect the computers each other's through network for communication or exchange the data. It is a wide complex to secure the data while transmitting the data between the system/networks. The intrusion detection is a mechanism to protect the data. There are various existing mechanisms for intrusion detection namely neural network, data mining technique, fuzzy logic, statistical technique etc. In this paper, Principal Component Analysis is applied to reduce the features and Gini index C5 algorithm is used to investigate and evaluate the efficiency and false positive rate. The benchmark KDD dataset is used to evaluate the efficiency and minimize the false positive rate using Gini index C5 algorithm and compare with other algorithm which shows significant improvement and to experiment the KDD Dataset to improve the efficiency and minimize the false positive rate using MATLAB software and demonstrated with the KDD dataset.