The main component (effective substance) of fatliquor can be attributed to two parts: neutral oil and emulsified component. The ratio of neutral oil and emulsifier is an important indicator for evalsuating fatliquor. The fatener has a high content of emulsifier, the self-emulsification ability of the fatliquor is strong, and the emulsion stability is good, which is favorable for the combination of oil and fat. However, the neutral oil content is reduced, and the lubrication and moisturizing effect are reduced. Therefore, there is an appropriate balance between the emulsifier portion and the neutral oil portion in the fatliquor, depending on different products and different requirements. As an important part of the fatliquor, the emulsifier can directly add the corresponding class of surfactant to the oil component to form a fatliquor of the external emulsion system. The fatliquor prepared by this method has poor application properties and is rarely used at present. At present, a hydrophilic group is introduced into a water-insoluble oil molecule by chemical modification to form a fatliquor of a self-emulsifying system. It can be seen that the chemical modification method is an important means for imparting different characteristics to the leather fatliquor.