NOVELTY - Preparation of back surface field silver paste of environment-friendly crystalline silicon solar battery, comprises: (a) preparing the glass dust of boron-zinc-bismuth series; (b) preparing the organic bond; (c) taking 0.1-0.5 pts.wt. of glass dust of the boron-zinc-bismuth series, 1.4-1.6 pts.wt. of the organic bond, and 6.5-7.5 pts.wt. of ultra fine silver powder; and fully grinding the mixture; and (d) adding 0.6-0.8 pts.wt. of the organic bond and 0.4-0.6 pts.wt. of diluent into the mixture, uniformly stirring; and obtaining the product.    USE - The process is useful for preparing back surface field silver paste of environment-friendly crystalline silicon solar battery (claimed).    ADVANTAGE - In utilizing the process, the prepared slurry does not contain lead (Pb), cadmium (Cd), mercury (Hg), or chromium, which is forbidden by European Union Restriction of use of certain Hazardous Substances (RoHS), and fits the instruction 2005/84/EC of European Union RoHS on phthalic acid ester. Moreover, it reaches environmental protection and is beneficial for the export of domestic crystalline silicon solar battery.    DETAILED DESCRIPTION - Preparation of back surface field silver paste of environment-friendly crystalline silicon solar battery, comprises: (a) preparing the glass dust of boron-zinc-bismuth series: weighing materials comprising 45-55 wt.% of bismuth oxide (Bi2O3), 20-30 wt.% of zinc oxide (ZnO), 20-25 wt.% of boron oxide (B2O3), 0-4 wt.% of aluminum oxide (Al2O3), 0.5-4 wt.% of silicon dioxide (SiO2), 0-4 wt.% of calcium oxide (CaO), and 0-4 wt.% of titanium dioxide (TiO2); uniformly mixing the materials, putting the mixture into high temperature resistance furnace; where the temperature of the furnace is controlled at 900-1200 degrees C; preserving the heat for 30-60 minutes; quenching the melted mixture via deionized water; ball milling to grain diameter of 0.5-2 mu m; screening via 200-400-mesh sieve to obtain the glass dust of boron-zinc-bismuth series; and setting aside for use; (b) preparing the organic bond: taking the raw materials comprising 0.8-1.2 pts.wt. of ethocel, 0.3-0.7 pts.wt. of epoxy resin, and 0.3-0.7 pts.wt. of phenolic resin; adding 7-9 pts.wt. of solvent, and heating at 90-120 degrees C; completely stirring the mixture until the mixture is dissolved; and obtaining the flaxen transparent organic bond; (c) taking 0.1-0.5 pts.wt. of glass dust of the boron-zinc-bismuth series obtained in (a), 1.4-1.6 pts.wt. of the organic bond obtained in (b), and 6.5-7.5 pts.wt. of ultra fine silver powder with average grain diameter of 0.2-1 mu m; and fully grinding the mixture; and (d) after the mixture is ground to fine and smooth particle, adding 0.6-0.8 pts.wt. of the organic bond and 0.4-0.6 pts.wt. of diluent into the mixture, uniformly stirring; and obtaining the back surface field silver paste of environment-friendly crystalline silicon solar battery.