The invention provides a chalcone isomerase gene of asparaguses, a protein encoded by the chalcone isomerase gene and application of the chalcone isomerase gene. The CDS sequence of the chalcone isomerase gene AoCHI1 is shown as SEQ ID NO: 1; the amino acid sequence of the protein encoded by the gene is represented by SEQ ID NO: 2. The chalcone isomerase gene AoCHI1 is cloned from the asparagus for the first time, and is one of key genes for synthesizing plant flavonoids; by the adoption of a method of gene engineering, the gene AoCHI1 is transferred into a target plant, so that the total flavonoids content of a transgenic plant can be increased, to improve the plant quality by using a gene engineering technology in the future; furthermore, an important theoretical basis is provided for obtaining medicines or food with high oxidization resistance, and the chalcone isomerase gene has a wide application prospect and high economic value.