Skin that is not smooth with small particles may be keratosis pilaris, cornu rashes, acne pimples, etc. 1. Keratosis pilaris: the pathogenesis is not clear, may be related to genetic factors, vitamin A deficiency, metabolic disorders, will cause the skin to have a special roughness, resulting in the skin with a needle tip to chestnut grain size follicular pimples, the appearance of the chicken skin-like changes, will cause the skin is not smooth with small particles of the symptoms. 2. Corns: are retention cysts originating from the epidermis or epithelium of the appendages, causing white bumps of pinpoint size on the skin, which can also cause the skin to be not smooth with small particles. 3. Acne vulgaris: It is associated with exuberant secretion of androgens, keratinization of the sebaceous gland ducts of hair follicles, and propagation of Propionibacterium acnes, which can also cause non-smooth skin with small particles. There may be other reasons why your skin is not smooth with small particles, so you need to go to the hospital for examination, clarify the cause of the disease, and actively treat it.