The invention discloses a preparation method of a micro-mesoporous structure Beta molecular sieve. The method comprises the steps that tetraethylammonium hydroxide, deionized water and sodium hydroxide are stirred, dimeric surfactant and sodium metaaluminate are dissolved in the mixture to continue to be stirred, finally, gas-phase silicon dioxide is dissolved in the mixture to continue to be stirred, and white silica-alumina colloid is obtained; the white silica-alumina colloid is paced in a reaction kettle to be heated for a reaction, the product is washed, produced and calcined after the reaction is finished, and the micro-mesoporous structure Beta molecular sieve is obtained. The gas-phase silicon dioxide, the sodium metaaluminate, the dimeric hyamine surfactant and the like are used as the raw materials to synthesize the micro-mesoporous structure Beta molecular sieve with the high degree of crystallinity and high specific area. The mesoporous content in the synthesized micro-mesoporous structure Beta molecular sieve is 53.20%, and the micro-mesoporous connectedness is high.