When the child’s first molar is black, it can be treated separately: 1.When the first and second molar form deep caries, a sharp digging spoon can be used to scrape away the decay, and then the cavity can be flushed with hydrogen peroxide solution, disinfected with alcohol and placed with calcium hydroxide cushion, and then filled with silver amalgam, etc. 2.When the X-ray shows that the cavity of the molar reaches the pulp cavity, the pulp needs to be removed under local anesthesia, and the metal preformed crown can be made after the root canal treatment is completed. 3.When the child’s milk tooth is brittle and easy to split, hold the tooth by hand during the process of grinding away the decay to prevent the crack. 4.When the first permanent molar newly erupted by the child is black, use the sharp and fine fissure drill to grind away the discolored tooth tissue and apply the flowing resin to fill the sulcus gap to prevent the expansion of the caries.