Abstract: The microscope, energy dispersive X-ray spectroscope (EDX) and ICP were used to analyze the composition of suspended matters in jet fuel. Combined with Amorphotheca resina`s （typical fungus）growth in jet fuel, the formation mechanism of suspended matters was proposed. It is concluded that the flocculent suspended matter in jet fuel is the outcome of multiple factors. The fungus, fibre and particulate impurities all participate in the formation of suspended matters.