Based on high-precision, high-quality data on SiO₂, Al₂O₃, Fe₂O₃, and organic matter in topsoils obtained from the 1:250,000-scale multi-purpose regional geochemical survey in Fujian Province, this study assessed topsoils and, for the first time, established a geochemical method-based geochemical assessment system for desertified land in the province. Specifically, this system involves methods for calculating the silicon-aluminum-iron ratio (Saf), carbon-silicon ratio (K_Si), and their comprehensive index value (Szh_ f), which serves as the indicator for assessing the degree of land desertification. Specifically, a higher Szh_ f value indicates a higher degree of desertification, and vice versa. Furthermore, this study determined the statistics of geochemical classification parameters for desertified land in Fujian Province and delineated the distribution ranges of geochemical grades. This aims to assess the current status of desertified land in the province from the microscopic perspective of soil elements and to further ascertain the distribution characteristics of the land. The results indicate that the land with strong, moderate, slight, and very slight desertification in Fujian Province exhibits areas of 39 531 hectares (0.326%), 65,790 hectares (0.542%), 103 601 hectares (0.853%), and 360 329 hectares (2.968%), respectively, primarily distributed along the coastal zone to the south of the Minjiang River and in Changting County of Longyan City. Field verification demonstrates that this evaluation method is scientific and reliable and yields accurate classification results of desertification grades, thus objectively reflecting the distribution status of desertified land in Fujian Province.