The study was conducted to find out suitable flame proofing on silk fabrics and to examine closely the flame retardancy effect and the physical properties changes of the silk, which was dyed by natural dyes and synthetic dyes, treated with agent (Diphenylbutylamidophosphate (DPBAP)). The results of the study were as follows: 1) Silk could be treated with DPBAP easily soluble in water by means of simple Pad-Dry-Cure. 2) The add-on of silk fabrics dyed by natural dyes was more than that of silk fabrics dyed by synthetic dyes. 3) The silk fabrics dyed by india ink among natural dyes has more flame retardancy effect in before treating with flame proofing agent than in after treating with it. 4) The physical properties (stiffness and tensile strength) of the silk fabrics treated with flame retardancy agent were little changed.