Weakness of both legs can be seen in the following causes: 1, long time in a sitting position, slow blood flow in both lower limbs leads to muscle weakness and weakness; 2, lack of daily exercise, slow blood circulation after stopping exercise leads to weakness of both lower limbs; 3, blood system diseases, such as anemia. Because of the reduction of red blood cells and oxygen content in the blood, patients have poor tolerance to oxygen deficiency, resulting in weakness of both lower limbs; 4, depressed patients usually have less activity and depressed mental state, lack of activity can lead to weakness of both lower limbs; 5, common vitamin and trace element deficiencies: such as lack of vitamin A, vitamin D, vitamin E and iron deficiency, calcium deficiency can lead to weakness of both lower limbs; 6, Chinese medicine believes that liver deficiency The weakness of both lower limbs can be caused by deficiency of liver, spleen and blood.