To construct an engineered Saccharomyces cerevisiae producing high titres of amorpha-4,11-diene, we investigated the possible synergistic effect of different vectors containing amorpha-4,11-diene synthase(ADS) gene within one yeast cell. We constructed the ADS recombinant plasmid pGADADS. This plasmid and another ADS recombinant plasmid pYeDP60/G/ADS were alone, or co-transformed into yeast Saccharomyces cerevisiae W303-1B and WK1, respectively, resulting in the following engineered yeasts, W303B[pGADADS], W303B[pYGADS], W303B[pYGADS+pGADADS], WK1[pGADADS], WK1[pYGADS] and WK1[pYGADS+pGADADS]. All of the six strains were cultured for GC-MS analysis of amorpha-4,11-diene. The results showed that all of the engineered yeasts could produce amorpha-4,11-diene. The yield of the product was improved with increasing ADS gene copies while no deleterious effect on the strain growth was found. Moreover, the product yield of the engineered yeast co-transformed with multiple plasmids was much higher than the total yield of the different engineered yeasts with only one plasmid, respectively. In conclusion, there was a distinct synergistic effect between different recombinant ADS plasmids within one cell. Our results facilitate the construction of the engineered yeast with high yield of amorpha-4,11-diene, the precursor of artemisinin.