This paper deals with simulator development for an underwater aquaculture surveillance system. The aim is to prevent the intrusion of objects into the water. The simulator checks the performance of the alarm system prior to installation in the underwater surveillance system. The simulator tests virtual environments, but reliable experimental results are obtained using two different methods. First, the state space underwater intruder dynamic models is expressed to control several variables at once. Second, the sensor model is designed using a statistical approach, because detection performance decreases for a various reason when detecting objects using the sensor. This simulator uses Matlab GUI as a tool. Setting various test environments (i.e., sensor configuration and sensor detection range) allows the user to analyze the performance of the underwater surveillance system.