Based on the threshold-arithmetic algebra system and guided by HE map, the threshold controllable switch of Schmitt inverter is analyzed, and the ternary current-mode CMOS Schmitt inverter is designed. The simulation results of Hspice show that the designed circuit has correct logic function and good transient characteristics. This circuit design not only makes the design of the threshold-arithmetic algebraic system further improved, but also makes the design of the ternary Schmitt inverter more simple and intuitive.