Cracked tongue usually indicates deficiency of yin and blood, whether it is serious and related to kidney needs to be judged by other symptoms. Cracked tongue refers to the tongue surface with cracks and grooves, commonly found in the front part of the tongue and the tip of the tongue on both sides, the cracks are usually of different depths, shallow as a scratch, deep as a knife cut, which mainly represents the deficiency of yin and blood. However, tongue diagnosis is usually a combination of tongue color, tongue texture, tongue shape, tongue coating, cracked tongue is only part of the tongue shape, so it is difficult to judge whether it is a kidney yin deficiency only through the cracked tongue. If the tongue is reddish-red, less moss dry cracked for heat injury to the yin or yin deficiency fire (Yin essence loss in the body, the emergence of hyperactive fire); tongue light and cracked for the blood deficiency; tongue cracked and broken common in the elderly yin deficiency. If, in addition to the cracked tongue, there are symptoms such as lumbar and knee weakness (a feeling of weakness in the lumbar and knee areas), five heart heat (heat in the hearts of the hands and feet, and self-consciousness of the heart and chest), then it is possible that the kidney yin is deficient, and for the judgment of the severity of the situation, it is recommended that you consult with a traditional Chinese medicine practitioner for a four-diagnosis combination, which is much more accurate. When discomfort occurs, one should consult a doctor in time and choose medication under the doctor’s guidance, not self-medication.