Abstract: Insitu monitoring of uniaxial tensile tests for 2.25Cr1Mo0.25V steel was carried out based on the acoustic emission (AE) technology. The evolution of the tensile damage state was comprehensively and accurately evaluated by utilizing multivariate AE features. The results indicated that multivariate AE features could significantly distinguish different damage stages of materials during the tensile process. The correlation method between the AE centroid frequency and amplitude, information entropy, and other time-domain parameters could provide reliable safety warning indicators for tensile fracture failure. The research findings could serve as a reference for AE monitoring and failure warning of metallic materials and structures.