The leather obtained through the traditional technique of “cleaning leather”, used for shadow puppets, possesses unique characteristics, such as a hard texture, resistance to bending, good transparency, and a high concentration of hydrophilic groups, setting it apart from typical soft leather. However, the conservation of shadow puppet artifacts made from this kind of leather has received limited attention in academia, with many studies even incorrectly equating the leather used for these artifacts with regular tanned leather, thereby overlooking its distinct material properties. Therefore, this study employed shadow puppet leather as a standard sample, subjecting it to controlled artificial aging processes and conducting assessments through microscopic observation, performance testing, and infrared spectrometry. This method explores the specific characteristics of environmental factors in the deterioration of leather. This study introduces two innovations:1) it proposes a method suitable for quantitatively assessing the aging and degradation of shadow puppet leather—a method characterized by small sample size, ease of operation, and cost-effectiveness; 2) based on this method, the practical assessment of shadow puppet leather demonstrates that even without the effects of tanning, the leather retains a significant degree of chemical stability through the mechanical leather-making process only.