In　this　paper,　automatic　control　of　the　water　level　in　an　irrigation　canal　by　automatic　regulation　of　intermediate　gates　was　studied.　Previous　scholars　have　proposed　a　water　level　difference　control　strategy　that　works　to　keep　relative　deviations　in　all　pools　the　same　for　a　particular　situation　where　the　operator　does　not　have　full　control　over　the　canal　inflow,　with　the　centralized　linear　quadratic　regulator　(LQR)　control　method　used.　While　in　practice,　the　deviation　tolerance　of　pools　may　differ　in　some　canals　which　limits　the　applicability　of　the　control　strategy.　In　this　work,　a　weight　coefficient　was　added　to　the　deviation　and　the　algorithm　was　improved　to　keep　the　relative　deviations　to　certain　proportions.　The　model　predictive　control　(MPC)　method　was　then　used　with　this　improved　control　strategy　and　was　compared　to　the　LQR　control　method　using　the　same　control　strategy.　The　results　showed　that　the　improved　strategy　can　keep　the　water　level　deviations　in　all　pools　to　certain　proportions,　as　is　our　objective.　Also,　under　this　difference　control　strategy,　the　MPC　method　greatly　improved　the　control　performance　compared　to　the　LQR　control　method.