The invention discloses genetically engineered rhodobacter sphaeroides, a preparation method thereof and a farnesol production method. A phosphatase PgpB gene from Yersinia pestis CO92 is transformed into rhodobacter sphaeroides and can be subjected to intracellular expression, and phosphatase PgpB with activity is generated, so that arnesyl pyrophosphate accumulated in the MEP pathway of rhodobacter sphaeroides can be directly catalyzed to generate farnesol.