The present invention provides a hydrocracking catalyst having high activity, high medium oil selectivity, catalyst constitute uses amorphous silica-alumina as a carrier, Y type molecular sieve processed by special modification is an acidity component, the molecular sieve has a high crystallinity and a lower cell parameter, a plenty quadric hole, larger surface, in addition, has a small acid center, even distribution, no strong acid center, 70-80% is moderate intensity acid center, 20-30% is weak acid center, and the molecular sieve also has a strong anti-nitrogen ability and better damaging ability, the hydrocracking catalyst using the molecular sieve has a better hydrocracking activity, and a higher medium oil selectivity, and a strong anti-nitrogen ability at the same time. The invention uses heavy hydrocarbon single stage or single stage serial hydrocracking process generate midbarrel oil product, and has better activity and medium oil selectivity.