The invention provides a [beta]-carotenoid ketolase mutant, which is obtained through a directed evolution means, nucleotide sequences for encoding the mutant, a recombinant expression vector containing a mutant gene, expression in saccharomyces cerevisiae and application of a genetic engineering bacterium in the synthesis of keto-carotenoids. According to the invention, a mutant strain with catalytic activity on [beta]-carotenoid enhanced is screened by virtue of a high-throughput screening method, and through gene sequencing analysis, mutant sites are subjected to combined mutation, so that the catalytic activity is further enhanced; and the screened mutant strain is applied to the production of saccharomyces cerevisiae keto-carotenoids.