The invention discloses a clastic rock reservoir diagenesis phase transverse prediction method based on a well. In the method, the six geological parameters of sedimentary facies, lithology, a pH value, a sedimentary cycle, a diagenetic stages and a fault index are taken as a clastic rock reservoir diagenesis phase type boundary constraint condition. Well diagenesis phase data is combined, diagenesis-phase transverse distribution is predicted, and insufficiencies in the work of a diagenesis-phase transverse prediction research aspect in the prior art are overcome. The method can be used to determine the validity of a reservoir and provide a basis for reservoir evaluation.