Tremor in the index finger of the left hand of a woman is clinically known as tremor. Tremor may be caused by physiological reasons such as excessive finger activity and mental stress, or it may be caused by pathological reasons such as Parkinson’s disease and hyperthyroidism. 1. Physiological reasons: prolonged and high-intensity activities of the fingers can lead to tonic contraction of the finger muscles and muscle bundle tremor, which is manifested as trembling of the fingers. In addition, a high degree of mental tension or shock will lead to transient sympathetic excitation, and the local muscles will reflexively tremble, which may also be manifested as tremor of the left index finger. 2. Pathological causes: when the nervous system has degenerative lesions, it may also lead to finger tremor, typical diseases such as Parkinson’s disease, Parkinson’s will lead to neurotransmitter secretion abnormality, local muscle excitability increases, and tremor occurs. Hyperthyroidism patients may also experience the above symptoms, which is mainly due to the increased synthesis and secretion of thyroid hormones, resulting in increased local muscle contraction speed and tremor. The tremor of the left index finger may also have other causes, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.