The causes of greasy hair after washing may be genetic factors, dietary and living habits, seborrheic dermatitis, endocrine disorders and so on. 1. Genetic factors: greasy hair after washing may be related to genetic factors, it is recommended to wash your hair frequently to keep your scalp clean, which can reduce the symptoms. 2. Diet and lifestyle: Irregular diet and lifestyle can also lead to greasy hair after washing, such as frequent intake of high-fat, high-sugar and spicy food, or often stay up late patients, can lead to scalp oil secretion. 3. Seborrheic dermatitis: after washing hair is still greasy may be related to seborrheic dermatitis, seborrheic dermatitis is a chronic inflammatory skin disease, when seborrheic dermatitis of the scalp, can be manifested as hair oil, dandruff, alopecia and other symptoms. 4. Endocrine disorders: after washing the hair is still greasy with endocrine disorders, when the endocrine disorders, androgen secretion is more, can lead to an increase in scalp oil secretion, manifested as scalp oil, greasy. Patients who are still greasy after washing their hair are advised to go to the hospital in time to clarify the cause of the disease and under the guidance of the doctor to carry out professional treatment.