Central precocious puberty (CPP) is mainly caused by the premature activation of the hypothalamic-pituitary-gonadal axis, which leads to abnormal hormone levels and triggers structural and functional changes in the brain, making the neurovascular coupling mechanisms of children with CPP different from those of normal children in the task state. Addressing current limitations of clinical diagnosis, such as false negatives, interference from obesity, and physiological discomfort, this study utilized functional near-infrared spectroscopy (fNIRS) to analyze task-related brain activation characteristics in 167 children from Tianjin Hospital, including 85 normal children and 82 children with CPP. An auxiliary diagnostic model for CPP was established based on these analyses. It was found that the prefrontal activation areas during mental arithmetic (MA) were more in the normal group than in the CPP group, and the activation areas were more in females than in males. By selecting mean, variance, kurtosis, and skewness from the two channels with the highest frequency of correlation and the highest magnitude of negative correlation as input features, the constructed classification model achieved an accuracy rate of 79.1%. This study provides a new and important reference for the rapid screening and pathogenesis study of CPP.