The synthesis problem of sliding mode variable structure control is investigated for a class ofuncertain Delta operator system with internal parameter perturbation and external disturbance.The differences and similarities of designing sliding mode controller based on two types of idealreaching law and exponential reaching law.The proposed methodsbring previous related conclusions of continuous time system and discrete-time system into unified delta operator system.Slidingmode control system designed by employing two types of reaching lawsnot only can reach the region of the switching surface in finite time,but also decrease the system chattering effectively.The simulation results illustrate the the feasibility and validity ofthe proposed approaches.