The present invention relates to the technical field of biological synthesis engineering and microorganism manufacturing, and provides a method and a microorganism for heterologous synthesis of patchouli alcohol, specifically a method for heterologous synthesis of sesquiterpene patchouli alcohol through a microorganism. The method mainly comprises: optimizing the codon of patchouli alcohol synthetase, assembling and expressing the synthetic downstream pathway, and strengthening the microorganism terpene synthesis precursor IPP/DMAPP so as to finally achieve the efficient synthesis of the patchouli alcohol in the microorganism.