Abstract: A silicon rubber was used as toughener and a phosphorous-nitrogen complex as the flame retardant in the non-halogen flame-retardant glass fiber/nylon 66 composite system. The effects of silicon rubber mass fraction on the mechanical properties, heat distortion temperature (HDT), flame retardancy and rheological property of the composites were studied, and the dispersion morphology of the silicon rubber in the matrix was also examined. The results show that the material had the best comprehensive properties when the content of the silicon rubber was 6wt%, its notched impact strength increased by 8%, comparing with the composite without silicon rubber, its tensile properties was above 85% of that of the compoite without silicon rubber, and it could achieve UL-94 V-0 rating. With the increase of the silicon rubber content, the HDT of the composite decreased, as for the apparent viscosity, however, increased until the content was 12 wt% and then experienced a decrease. The silicon rubber was sheared to fiber-like and distributed in the composite, and it would aggregate when the content of silicon rubber reached 9wt%.