The invention discloses a liquid fertilizer filling machine. The liquid fertilizer filling machine comprises a base, a vertical frame, an air cylinder, a sliding seat, a filling tube, a filling nozzle, a vertical plate, a support plate, a driving mechanism, a rotating shaft and a cam, wherein two guide sleeves, a push rod, a cylinder body, a piston, a first one-way valve, a second one-way valve, asoft connector, a sliding plate, a guide wheel, a limiting ring, a first spring, a support, a material barrel, a liquid inlet pipe with the elbow being arranged at the bottom, a buffer mechanism anda filtering mechanism are arranged in parallel with the support plate. According to the liquid fertilizer filling machine, the structure is simple, each time the cam rotates once, the liquid fertilizer in the material barrel is sucked into the cylinder body and a packaging bottle is filled with the liquid fertilizer with equal volume, so that the automatic and quantitative filling is realized; meanwhile, the filling nozzle is adopted for sealing filling, the liquid fertilizer is prevented from splashing, the waste of raw materials is avoided, and the environment of the working site is prevented from being polluted.