In this study, we conducted the study about improvement of characteristic in flame retardancy and mechanical property. when flame retardant is added to natural fiber composites using poly-propylene(thermoplastic resin), epoxy(thermosetting resin) and two kinds of flame retardant, ATH and Nanoclay. According to arranging method, natural fiber is divided into uni-direction, bi-direction and random-direction. We quantitatively measured mechanical behavior and characteristic of resistance to flame based on content degree of flame retardant after manufacturing composites using those three types of natural fiber. Through tension test, tensile strength and flexural strength are the biggest when we use fiber which is arranged to uni-direction. and also, it is verified that as content degree of flame retardant is increased, mechanical behavior is decreasing but Heat release late is increasing.