The invention discloses an external surface cleaning device for an electrocardiogram instrument. The external surface cleaning device comprises a liquid storage shell, a liquid storage cavity, a protective cover, a liquid discharging pipe, a liquid discharging valve, a cleaning sponge block, a liquid discharging hole, a pushing rod, a piston, a liquid injection pipe, a one-way valve, a spring, a clamping groove, a pushing plate, a fixing rod and a rubber suction disc. The external surface cleaning device of the electrocardiogram instrument is simple in structure and novel in design, the integrated structure of washing liquid and the cleaning sponge block is achieved, a user can conveniently wash the surface of the electrocardiogram instrument, the washing efficiency of the electrocardiogram instrument surface is improved, meanwhile, the device structure is smaller, and the carry and use are facilitated; and when used, through the matched function of the arranged pushing rod, the piston, the liquid discharging pipe and the liquid discharging hole, the washing liquid is conveniently added at any time when the electrocardiogram instrument is wiped and washed, the washing efficiency during washing is improved, the time is saved, meanwhile, the spread of bacteria is avoided because the hands are prevented from being in contact with the electrocardiogram instrument during washing, and the external surface cleaning device is suitable for promotion to be used.