There are many causes of leg weakness and trembling, including natural physiological causes or nutrient deficiencies, muscle lesions, neuromuscular junction lesions or nerve injuries, etc., which can also be caused by extra-vertebral system diseases. When patients have the above symptoms, they should seek medical attention to clarify the cause, and then use the appropriate treatment under the guidance of a doctor.1, physiological reasons: as the saying goes, people get old before they get old legs, that is, with aging there will be natural weakness of both lower limbs, legs shaking symptoms. In addition, after strenuous exercise, also prone to leg weakness, shaking phenomenon; 2, nutrient deficiency: when the body of sugar, calcium, vitamins and other nutrients deficiency, may lead to hypoglycemia, hypocalcemia, may appear leg weakness, shaking. At this time, the cause should be clearly examined, under the guidance of the doctor to supplement the corresponding nutrition, should pay attention to nutritional balance, more fresh fruits and vegetables, milk, etc.; 3, muscle lesions: such as a variety of myositis, such as polymyositis, inclusion body myositis or myotonic dystrophy, can cause leg weakness, shaking, accompanied by fever, muscle joint pain and other symptoms; 4, neuromuscular junction lesions. Mainly manifested as pulsatile weakness and muscle fatigue, weakness symptoms always exist, but shivering symptoms significantly aggravated after activity, such as myasthenia gravis, myasthenia gravis syndrome; 5, nerve injury: any injury that leads to nerve innervation of the lower limb muscles can lead to muscle weakness, can be peripheral nerve injury, nerve root injury, can also be lumbar bulge and lumbar bulge below the part of the nerve, spinal cord injury 6, extravertebral diseases: many patients with Parkinson’s disease, for example, will also have weakness and shaking of the lower extremities, including chorea, dystonia and other diseases; 7, other: hip and knee osteoarthrosis, intracranial diseases leading to nerve damage, diabetes and other systemic diseases can also lead to the symptoms of weak legs and shaking. When patients have no strength and shaking legs, they should seek medical attention in a timely manner, and after clarifying the cause, correct treatment under the guidance of a doctor can alleviate the symptoms.