The invention relates to a preparing method for a ZSM-5/EU-1 composite molecular sieve with a core-shell structure characteristic. The preparing method includes the steps that a silicon source, an aluminum source, a template agent and sodium hydroxide are added into water to form a uniform gel solution, citric acid is added into the gel solution, the pH value of the gel solution is adjusted to be 10.5-11.5, the gel solution is subjected to a crystallization reaction for 1-4 days at the temperature of 140 DEG C-200 DEG C, the product is roasted to remove the template agent and then subjected to ion exchange with an acid solution, and the ZSM-5/EU-1 composite molecular sieve is obtained after roasting. The raw materials for synthesizing the composite molecular sieve are used by the molar ratio of Na2O:SiO2:Al2O3: tetrapropyl ammonium bromide: hexamethonium bromide: citric acid:H2O=(0.01-0.05):( 0.01-0.05):(0.0001-0.0005):( 0.0001-0.001):( 0.001-0.01):(0.5-1):(0.01-0.15).