In this paper an attempt has been made to modify the construction of one type of fabrics which are used to make outerwear cloths for soldiers in order to increase its service life. This modification could be achieved by means of knowing the optimum constructional factors of fabrics such as material used for weft yarns, Weft yarn linear density, pick density and weave design (average float length). The investigated mechanical properties that correlated with the end-use performance of the outerwear cloths of soldiers are fabric fatigue at repeated extension, relaxation characteristics of fabrics at extension, fabric endurance to repeated flexing, tensile load and extensibility of fabrics, flexing and abrasion resistance of fabrics and stiffness at bending Mathematical models describing these properties could be obtained, by using factorial design method, for predicting the service life behaviour of milltary fabrics. By using both the graphical and mathematical methods, it we found that the optimum fabric construction to make outer wear cloths for soldiers is recommended to be contained weft blended yarns (50% cotton/ 50% polyester) of 52/2 Ne (11.36 x 2 tex) at 60 picks/inch with using twill 1/2 weave design and with using warp specifications of article No. 2509.