The present disclosure provides a P450 cytochrome enzyme for andrographolide synthesis and its application, belonging to the field of bioengineering. The present disclosure uses Saccharomyces cerevisiae CEN.PK2-1D as a host, and implements knockout of ROX1 and GAL80 genes on the genome, and integrative expression of GGPP synthase encoding gene and CPS diterpene synthase encoding gene at ROX1 site; and implements free expression of ApCPR and CYP71A8 and CYP71D10 both with truncated signal peptides, successfully constructing recombinant S. cerevisiae, and achieving de novo synthesis of 3,15,19-Trihydroxy-8(17),13-ent-labdadiene-16-oic acid. Compared with the blank, a response value of a product peak reaches 1.9*106, and this strategy provides necessary reference for analyzing biosynthetic pathway of andrographolide and using metabolic engineering to synthesize andrographolide and related derivatives thereof.