This subject describes three main topics: (i) cellulosic materials' physical and chemical structure; (ii) cellulosic cure finishing and flame retardancy; and (iii) cellulosic and its composite cure of flame delay and fire. The first topic details various sources of cellulose and their chemical and physical structure. The second subject includes the application of flame retardant textile materials and describes the difference in the definition of retardant/resistant terms, and explains in more detail the theory of combustion or burning, and fire and flame retardant mechanism. Different phosphorous flame retardant synergistic were also mentioned, including the types and classifications of flame retardant finishes based on durability and nature. At the end of this section, various textile inflammability tests are described. The last part of the chapter shows the preparation by layer by layer of branched polyethyleneimine of A flame retardant surface Kaolin, urea and Phosphate (DAP) (BPEI).