The polyploid plants were obtained from the leaves of Sinningia Speciosa (Lodd.)Hiern treated by colchicine. Best result for inducing tetraploid was by adding colchicine20 mg L-1 intothe medium treated for one week rather than by colchicine soaking. Morpho-logical observation showed that the sterns and the leaves of tetraploid plants were respectivelythicker and lalger than the diploid ones. The chromosome number of tetraploid plants was 2n=4x=52, while that of diploid plants was 2n=26. Peroxidase isoenzyme analysis showed that the enzyme activities between the polyploid and the diploid plants were quite different．Two new bands were observed in the isoenzyme map of tetraploid plants．