The invention relates to a boron fluorescent testing method. According to the method, boron is reacted with alizarin red to form a stable yellow fluorescent complex, beta cyclodextrin is adopted as asensitizer, trace boron is tested by using a fluorescent method with high sensitivity and high selectivity, the boron concentration is within 0.05-1.0mg/L, and the relative fluorescent strength of thesystem is in a direct proportion to the boron concentration.