The invention discloses a non-dye fiber developing treatment method. The method comprises following steps: (1), a mixture of two colorless benzaldehyde derivatives and inorganic acid are mixed in an aqueousthickening agentsolution, and a mixture with viscosity reaching 10,000-50,000 mpa.s is obtained; (2), the mixture is taken and used for coating or scraping treatment on silk fabric; (3), the treated silk fabric is subjected to steaming treatment with saturated steam, and color fixation of the silk fabric is realized; (4), the silk fabric obtained in the step (3) is oxidized with an oxidizing agent under the acidic condition. According to the method, no dye or coloring agent is needed, the benzaldehyde derivatives of fibers can be subjected to a certain chemical reaction on the silk fibers in the presence of trace water or saturated steam, and fiber developing or dyeing is realized. The developing rate is up to 85%-95% or higher, and dyeing wastewater drainage can be substantially reduced; the developing reaction time is short, and energy consumption can be reduced.