In this paper, to deal with the problem of insufficient temperature resistance of existing filter loss reduction agents for natural materials, we have searched for a green material, grape extract (GE), that is resistant to high temperatures, and evaluated the filter loss reduction performance and filter loss reduction mechanism of GE for the first time. The structure of GE was firstly characterized by Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric experiments (TGA) showed that it had a good thermal stability. Subsequently, the effects of GE on the filter loss reduction of base slurry under high temperature conditions were evaluated by medium-pressure filtration loss and high-temperature and high-pressure filtration loss experiments, and the filter loss reduction mechanism of GE was analyzed by using zeta potential, particle size distribution, and scanning electron microscopy (SEM) experiments. The experimental results showed that after aging at 170 ℃ for 16 h, the medium pressure (API) filtration loss of the base slurry containing 3% GE was the smallest, 12.8 mL (less than 15 mL), and the high-temperature and high-pressure (HTHP) filtration loss at 120 ℃ was 24.0 mL, which was superior to those of the commonly used fluid loss controlling agent, carboxymethyl starch (CMS), polyanionic cellulose (PAC), and foreign polymer fluid loss controlling agent Driscal, and the filtration loss reduction effect of sulfonate copolymer (DSP-2) was comparable. GE has excellent performance in reducing the loss of filtration is mainly attributed to the strong adsorption on the surface of bentonite through hydrogen bonding and strong electrostatic effect, increasing the absolute value of the zeta potential of the surface of the bentonite, improving the electrical stability of bentonite at high temperatures, so that the bentonite at high temperatures is not easy to occur under the conditions of agglomeration, reducing the size of the bentonite, and better promote the dispersion of the bentonite, and the surface of the filter cake is smooth. In addition, the molecular structure of GE contains a benzene six-membered heterocyclic ring, this structure can enhance the rigidity of the molecular chain, it is not easy to curl and deform at high temperatures conditions, so that it maintains an excellent filtration loss reduction performance at high temperatures of 170 ℃. At the same time, the biotoxicity EC50 of GE is 133690 mg/L, which is greater than 30000 mg/L, and the biodegradability BOD5/CODcr of GE is 32.75%, which is greater than 5%, which indicates that it is non-toxic and easily biodegradable.