There are three main methods to test bone age, namely, counting method, calculation method and charting method. 1. Counting method: Bone age is short for age of bone development, which is an indicator of bone development. In this method, the X-ray film of the wrist is taken and the number of ossification centers is counted and then compared with the table to get the bone age, but it may be affected by the position of the wrist when the film is taken and may cause deviation. 2. Calculation method: It is mainly used to measure the area, shape and length of epiphysis, epiphyseal plate and diaphysis, or to calculate the relative proportion between them, and then the obtained values are used as parameters to determine the bone age after statistical processing. However, the measurement process is more complicated and standardization is difficult. 3. Atlas method: The main purpose is to compare the X-ray film of the subject’s wrist with the bone age standard X-ray film atlas, and take the most similar standard film as the subject’s bone age film, so as to get the specific bone age data. It is seldom used because of the relatively large margin of error that can occur. It is recommended to consult a doctor for a comprehensive evaluation of the condition to determine the exact method of bone age testing.