The invention discloses an oryza sativa autophagy-related protein OsATG8b (oryza sativa autophagy-related gene 8b) and application of a coding gene of the oryza sativa autophagy-related protein OsATG8b to improvement of heavy metal tolerability or accumulation of plants. Expression of the gene in engineered saccharomyces cerevisiae can improve cadmium tolerability of yeasts and reduce the content of cadmium in the yeasts, so that the protein OsATG8b shows a heavy metal cadmium detoxication capability. If the gene is expressed in engineering bacteria in a transgenic manner, on the one hand, heavy metal cadmium tolerability of the engineering bacteria can be improved, on the other hand, heavy metal cadmium accumulation in transgenic saccharomyces cerevisiae can be reduced, and accordingly the engineering bacteria can be applied to microorganism genetic modification engineering aiming at heavy metal cadmium pollution. The gene has a potential to be applied to cadmium-resistant genetic engineering breeding of plants, and by regulation of expression of the gene in the plants, heavy metal cadmium tolerability of transgenic plants can be changed, heavy metal cadmium accumulation in the transgenic plants can be changed as well, so that the problem of quality decline caused by cadmium enrichment of agricultural products acquired from heavy metal cadmium polluted soil is solved. The gene has a potential to be applied to low-cadmium or cadmium-resistant genetic engineering breeding of crops.