Fuente: WIPO "tobacco agriculture" The invention provides a codominant SSR (simple sequence repeat) marker closely linked with a hydrocyanic acid release amount gene qHCN in mainstream smoke of tobacco and an application method. The serial numbers of the codominant SSR marker closely linked with the hydrocyanic acid release amount gene qHCN in the mainstream smoke of the tobacco are TM22844 and IDYK17653, and the nucleotide sequences of PCR (Polymerase Chain Reaction) amplification products of the codominant SSR marker closely linked with the hydrocyanic acid release amount gene qHCN in the mainstream smoke of the tobacco are respectively shown as SEQ ID No.1, SEQ ID No.2, SEQ ID No.3 and SEQ ID No.4. The application is the application of the codominant SSR marker closely linked with the hydrocyanic acid release amount gene qHCN in detecting whether the hydrocyanic acid release amount gene qHCN exists in tobacco genome DNA (Deoxyribose Nucleic Acid) or not. Compared with a method in the prior art, the codominant SSR marker has the characteristics of accuracy, high efficiency, stability, convenience, low cost and no detection opportunity limitation, so that the molecular marker can be applied to auxiliary selection of the molecular marker of the hydrocyanic acid release amount gene qHCN in low-harm tobacco breeding.