Objective To develop a portable automatic tourniquet.Methods Using microcomputer and pressure sensor,the pressure and hemostatic time of current pressurized tourniquet were controlled.Results Portable automatic tourniquet was composed of gasbag pressurized bandage,electric micro-pump,pressure sensor,preamplifier,impact damper,A/D converter,single-chip micro-computer controller,data memory,keyboard and its interface circuit,display and its interface circuit,photoelectronic control circuit,etc.Conclusion Portable automatic tourniquet is small,light,safe and convenient.Besides,rapid hemostasia and automatically controlled & stable pressure enable it to be used both in the war and at peace time.[Chinese Medical Equipment Journal,2008,29(2):21-23]