Abstract: Carbon fibric reinforced cementitious matrix (CFRCM) is often used in the reinforcement of concrete structures and self-sensing structures. However, the mechanism of piezoresistive response is still unclear. In this paper, through the pull-out test of CFRCM, it is found that the load-displacement curves present typical three-stage characteristics of bond-slip model, and the change of resistance during the pull-out test also presents three-stage characteristics, which contains random fluctuation rising, rapid growth and slow growth stages. Further analysis shows that the growth rate of resistance in the debonding stage of carbon fiber bundles has a medium-high positive correlation with the ultimate pull-out force. An equivalent delamination failure model and calculation method of carbon fiber were established based on the piezoresistive response of carbon fiber bundles in the pull-out progress, which realized the mutual conversion between the resistance information and the charged state.