Abstract: In order to study the effect of reinforcement ratio on fracture property and acoustic emission characteristics of Ⅰ-Ⅱ mixed-mode fracture in concrete, four groups of three-point bending beams with a straight offset notch in reinforced concrete were used for Ⅰ-Ⅱ mixed-mode fracture experiments and collection of acoustic emission signals. The test results were analyzed. The results show that with the increase of reinforcement ratio, the unstable load increases approximately linearly, and reinforcement ratio can influence Ⅰ-Ⅱ mixed-mode fracture mode of concrete. There were several peaks in the ringing counts during the stable fracture propagation. The abrupt change of the cumulative counts could represent the critical states of Ⅰ-Ⅱ mixed-mode fracture, and the three parameters had strong correlation. The peak frequency points of acoustic emission concentrated in different frequency bands. Starting from the 85% load level, the proportion of frequency band in 140~155 kHz decreased, while proportion of frequency band in 30~45 kHz increased. When specimens approached the unstable critical state, the peak frequency distribution tended to disperse.