The invention discloses a storage battery for an electric tool for a garden and an automatic injecting device for electrolyte of a storage battery. The storage battery comprises an electrolyte storing tank, a liquid delivery pipe, a peristaltic pump, an electrolyte adding cap, a vent cap and a storage battery body, wherein the storage battery body consists of an ABS (Acrylonitrile Butadiene Styrene) casing, a top cover, a positive terminal, a negative terminal, AGM separators, positive plates and negative plates; the bottom end of the positive terminal is connected with the positive plates; the bottom end of the negative terminal is connected with the negative plates; electrode lug connecting slots of which openings face upwards are separately formed inside the positive terminal and the negative terminal; the inner part of the electrode plug connecting slot of the positive terminal is in threaded connection with a positive electrode plug; the inner part of the electrode plug connecting slot of the negative terminal is in threaded connection with a negative electrode plug. Assembly and disassembly of the positive electrode lug and the negative electrode lug, injection of the electrolyte, and exhaust of air are facilitated; by means of the peristaltic pump, the electrolyte in the electrolyte storing tank is conveniently extruded forwards by the liquid delivery pipe in the rotating direction of a center wheel, and corrosion caused by contact between the electrolyte in the liquid delivery pipe and the peristaltic pump is also effectively avoided; quantitative injecting of the electrolyte is realized.