Abstract: The floccule appeared in the jet fuel of hydrocracking in freeze point test and disappeared when the oil temperature rose. By adjusting the blending ratios of FCC diesel, purchased wax oil and CDU diesel in the raw materials, the aromatic hydrocarbons and n-alkanes components in the raw materials were reduced, the suspended substances were still found in the freezing test, while measures by adjusting the operating conditions, the fractionator effect, the jet fuel distillation range and the other factors affecting the quality of the jet fuel could not eliminate the presence of suspended matter. The laboratory analysis found that no suspension appeared for dried jet fuel. It is the water from air dissolved in the oil that causes the appearance of floc. Therefore, measures must be taken to isolate water when jet fuel is tested at freezing point.

Key words: jet fuel, floccule, freeze point, hydrocracking, test method