The invention discloses an environment-friendly electrode silver slurry of zinc oxide varistor suitable for two soldering technologies and a preparation method of the electrode silver slurry. The silver slurry is composed of 60-80% silver powder, 1-5% of metal oxide, 2-5% of leadless glass powder and 10-37% of organic carriers by weight. The preparation method comprises the steps that the leadless glass powder is prepared by that raw materials are mixed well, placed in a platinum crucible and melt, and the melt material is removed and dried to obtain the leadless glass powder; the organic carriers are prepared by adding an organic solvent into a stainless steel container, adding organic resin, carrying out heating, and carrying out cooling and adding a surfactant after the resin is completely dissolved; and the silver slurry is prepared by mixing the silver powder, the metal oxide, the leadless glass powder and the organic carriers, and stirring and grinding the mixture in a vacuum manner. The preparation method is simple and suitable for both the reflow soldering and immersed soldering technologies, the solderability and the soldering resistance are high, the silver slurry can be used to prepare common type as well as lightning protection type varistor, the adhesion force, the conductivity and the electrical performance are high, and the performance completely reach the using requirements.