Abstract: In this paper,it uses microencapsulated red phosphorus which are the flame retardants and nano-SiO₂ which are the flexibilizers to manufacture flame-retardant polyester fiber splines by melt blending method,and study the effect of the amount of flame retardants and tougheners to the flame-resistant and mechanical properties of polyester. The results showed that microencapsulated Red Phosphorus can significantly enhance the flame retardant properties of polyester fibers splines,and nano-SiO₂ can improve the mechanical properties of the polyester fiber splines; When the content of microencapsulated red phosphorus was 5%,the polyester fiber splines exhibited a LOI value of 33,tensile strength of 17.99MPa,flexural strength of 26.75MPa,and impact strength of 1.97kJ/m²,and the mechanical properties of the materials declined seriously. When the content of microencapsulated red phosphorus was 3% and the content of nano-SiO₂ was 2%,the polyester splines exhibited a LOI value of 29,tensile strength of 35.51MPa,flexural strength of 31.54MPa,and impact strength of 2.03kJ/m².

Key words: microencapsulated red phosphorus, nano-SiO2, polyester, flame retardants, flexibilizer, limiting oxygen index(LOI)