The invention relates to a composite molecular sieve-containing medium oil type hydrocracking catalyst, which comprises an active component and a binder, wherein the active component adopts amorphous SiO2-Al2O3 as a carrier, adopts a composite molecular sieve as an acid component, and adopts a group VIB metal and a group VIII metal as hydrogenation activity components, and the composite molecular sieve comprises a Y molecular sieve and a ZSM-23 molecular sieve. According to the present invention, the deep dealuminzation modified Y molecular sieve has characteristics of high crystallinity, large surface area, high silica-alumina ratio, low cell constant, rich secondary pore, low acid center density, high moderate-intensity acid center ratio, and the like; the modified ZSM-23 molecular sieve has characteristics of smooth pore channel, less acid center and outstanding isomerism performance, wherein a light naphtha component is isomerized so as to increase an octane number of naphtha; the composite molecular sieve compounded from the Y molecular sieve and the ZSM-23 molecular sieve is adopted as the acid cracking component so as to provide advantages of the Y molecular sieve and the ZSM-23 molecular sieve, and compounding is performed according to the ratio of the present invention, such that the best catalysis effect can be obtained, and the obtained catalyst is suitable for the medium oil type hydrocracking catalyst; and the catalyst prepared from the composite molecular sieve has characteristics of excellent medium oil selectivity, good activity and good stability.