Abstract: SCADA refers to a large-scale, distributed measurement (and control) system. SCADA is not a specific technology, but a type of application. SCADA stands for Supervisory Control and Data Acquisition — any application that gets data about a system in order to control that system is a SCADA application. A SCADA application has two elements: 1. The process/system/machinery we want to monitor a control — this can be a power plant, a water system, a network, a system of traffic lights, or anything else. 2. A network of intelligent devices that interfaces with the first system through sensors and control outputs. Now modern SCADA system network are associated with large area through LAN/WAN. So automatically the secure security system of SCADA is necessary and for that in this paper we have propose a complete secure SCADA system base on the MiniSec, a secure network layer protocol for wireless sensor networks. By simulation we have shown that it will perform more securely then other SCADA system.