Weakness and trembling of the legs is a manifestation of decreased muscle strength of the lower limbs, and there are several common causes: 1, lumbar spine diseases or lumbar spinal cord lesions, such as lumbar disc herniation, lumbar spine fracture, lumbar spine tuberculosis, as well as lumbar spinal cord inflammation, spinal cord tumor, etc. Most of them are double lower limb weakness and trembling. Most of them are soft and trembling of both lower limbs, some of them are accompanied by incontinence, lumbar spine magnetic resonance examination can be clearly diagnosed. 2, intracranial diseases, such as cerebral infarction, cerebral hemorrhage, intracranial tumors, and viral encephalitis, etc., the local brain damage compresses the nerves, causing softness and trembling of one side of the lower limbs, which is mostly accompanied with headache, nausea and other symptoms, cranial magnetic resonance or cranial CT examination can be clearly diagnosed. 3, Parkinson’s disease is mostly found in middle-aged and elderly people, which will manifest itself at the beginning. Parkinson’s disease is mostly seen in middle-aged and old people, at the beginning, it will be manifested as trembling of one side of the lower limbs, which is obvious in the resting state, and with the passage of time, it can be progressed to trembling of one side of the lower limbs accompanied by softness.