| In this research, the effect of Fredkin gate on a system consists of four particles is considered. The number of states of this system is n=24=16, these states are (|0000>, |0001>, |0010>, |0011>, |0100>, |0101>, |0110>, |0111>, |1000>, |1001>, |1010>, |1011>, |1100>, |1101>, |1110>, |1111>). When Fredkin gate is applied on these states most of them remains without change except some of the states will be changed. The features of the gate process can be utilized in quantum information computations |