Abstract: In comparison with chrome-tanned leather, chrome-free leather commonly presents natural defects, such as strong hydrophilicity and insufficient fiber dispersion. Designing a suitable retanning agent for chrome-free leather by regulating its hydrophilicity would be an effective strategy to solve these problems. In this work, the effect of the hydrophilicity (carboxyl monomer content) of acrylic resin (AR) retanning agent, synthesized by using acrylic acid and long-chain alkyl methacrylate, on the properties of organic chrome-free leather was investigated. The decrease in AR particle size and the increase in its surface negative charge were observed with increasing carboxyl content, thereby resulting in the improved penetration depth and distribution uniformity of AR in the organic chrome-free leather. When the content of acrylic monomer was 45%, AR fully penetrated the organic chrome-free leather and achieved the highest degree of fiber dispersion and appropriate hydrophobicity, which endows the resulting crust leather with satisfactory dry heat stability, tearing strength, and tensile strength. These results indicate that designing AR with suitable hydrophilicity is of great significance to improve the comprehensive performance of chrome-free leather.