catalyst of this invention the raw material pp pe and ps are put into the reactor directly without any cleaning treatment the reaction temperature needed is 150 u00b0 c lower than those using the catalysts of other technologies also during the whole process of catalytic cracking the yield of lean gas decreases which increases the yield of the mixed hydrocarbon fractions by 3 the ratio of catalyst to raw material treated is 1 5 by weight when the catalyst of this invention used in a fixed bed reactor the temperature of reaction ranges from 280 u00b0 c to 480 u00b0 c where the optimal temperature ranges from 280 u00b0 c to 415 u00b0 c the pressure of the reaction system ranges from 0 01 to 0 04 mpa where the optimal reaction pressure is 0 025 mpa when the catalyst of this invention is used to decompose the waste plastics a mixture of liquid fractions with the distribution of hydrocarbons mentioned above can be obtained by one step process when the mixed hydrocarbon fractions are put into the storage tank the rectification can be proceeded directly to obtain gasoline and diesel oil and further processed by extraction reaction and fractionating so that other chemical products such as benzene toluene xylene butane and butadiene etc can be obtained further explanation to this invention the catalyst and preparation method will be given with reference to the following examples.