Grain forming process for heavy growing grains of original leather

The invention discloses a grain forming process for heavy growing grains of original leather. Part of leather which is screened from raw leather raw materials and has high growth line proportion or heavier growth lines is used as a raw material to carry out grain opening and flattening; the process comprises two times of soaking operation; in the soaking operation, the raw material cow leather isrespectively subjected to first soaking of edible salt water and alkali and second soaking of clear water and alkali; after water soaking is completed, treatment is conducted through a liming process,in the liming process, through reasonable design and graded addition of NaHS, Na2S and lime, the stretching effect of the leather material is guaranteed in cooperation with low-water-temperature treatment, and after water is added twice, the leather material with the leather lines naturally stretched and opened and subjected to grain opening treatment is obtained. The process can be used for solving the problem of heavy g