At present, animal bone glue (BG) is being widely used in many fields, but there are no studies reported on oilfield chemistry. In this paper, an environmental water-based drilling fluids additive named bromoethane-modified bone glue (BG) was developed by using bovine bone glue and bromoethane as raw materials, anhydrous ethanol as solvent, sodium hydroxide as alkaline hydrolysis agent, and sodium carbonate as a system pH regulator. The inhibition, filtration performance, and temperature resistance of BG were evaluated. Performance study results show that the linear swelling rate of sodium bentonite (Na-MMT) was decreased from 50.2% (in tap water) to 38.2% (in 4 wt % BG solutions), and filtration loss was reduced from 30 mL (in tap water) to 12 mL (in 5 wt % BG). Hot-rolling experiments show that the BG solution still exhibits good performance even after 16 h × 130 °C. The reasons for BG to achieve excellent performance were analyzed through scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ζ potential, thermogravimetric analysis (TGA), and microstructure. The results of SEM and FT-IR show that BG can fully dissolve in water and adsorb on the surface of clay particles by relying on its own adsorption functional groups such as −OH and −COOH. When 4% BG was added, ζ potential analysis revealed that the clay particle size declined by 0.502 μm, which indicated that BG can inhibit clay hydration swelling dispersion.