In order to intensify QTL fine mapping, mapbased gene cloning, functional analysis and molecular marker assisted breeding of the low hydrocyanic acid content trait of sorghumsudangrass, we used 500 isolated individual clone plants and their parents of diploid hybrid sorghumsudangrass F₂ generation population as materials, which was constructed in the early stage of the research group. The QTL mapping of hydrocyanic acid content trait of the highdensity molecular linkage map of sorghumsudangrass was determined by interval mapping method. The results showed that: (1) the generalized heritability of the hydrocyanic acid traits in the four different environments was 61.70%, 72.05%, 40.16% and 69.25%, respectively, indicating that the hydrocyanic acid content is both environmentally affected and controlled by microeffects. The frequency of population measurements showed a characteristic of singlepeak normal distribution, which met the QTL mapping requirements. (2) Under the condition of LOD>2.5, 16 QTLs related to hydrocyanic acid traits were detected, which were distributed on LG1, LG2, LG4, LG6, LG7, LG8 and LG10 linkage groups. (3) There are 9 stable QTLs that can be repeatedly detected in 16 QTLs, and the genetic contribution rate ranges from 1.17% to 39.9%. Among them, the main QTLs with contribution rate >20% are Qcn22, Qcn41, Qcn6 and Qcn61, a total of four. The experiment identified the genetic effects and molecular marker sites of each QTL.