The invention discloses gluten-free modified flour. Particle coverage rate of pickering emulsion prepared by adopting the gluten-free modified flour is higher than 20%. The invention further providesa preparation method of the gluten-free modified flour. By effectively controlling property of gluten-free flour, the preparation method of the gluten-free modified flour is capable of causing pickering phenomenon during dough fermentation process by producing particle-covered bubbles; and thus, gas-holding stability of the dough can be improved so as to have air chamber structure of gluten-free dough improved.