Composite plasticizer used for CL-20-based cast PBX explosive, and preparation method thereof

The invention provides a composite plasticizer used for a CL-20-based cast PBX explosive, and preparation method thereof. The composite plasticizer contains an ester compound and liquid paraffin; the general formula of the ether compound is shown in the description, and R1 and R2 in the formula are respectively selected from C6-C12 linear or branched alkyl groups. The composite plasticizer comprises, by weight, 1-99% and preferably 20-80% of the ether compound, and 1-99% and preferably 20-80% of the liquid paraffin. The composite plasticizer has the advantages of good intersolubility with HTPB, low water content, high purity, high combustion heat and good vacuum stability, and the CL-20-based cast PBX explosive applying the composite plasticizer has the advantages of high solid content, adjustable mechanical performances, good usability, short preparation time and low energy consumption.