The design technology of plane emergency gate slot form under pressure flow condition is good, but the hydraulic characteristics of plane emergency gate region are different from the plane working gate region under without pressure flow behind the gate. Based on six test results on hydraulic characteristics of plane working gate region of middle outlet at Jishixia hydraulic Power Station with the help of numerical solutions, the appropriate plane working gate slot form,i.e. an optimum scheme including expanding the offset of the slot, enlarging the radius of its downstream angularity and lowering the gradient behind the angularity, is recommended.