At present, the study of smart composite material of carbon fiber is mainly focused on the usage of the material pressure-resistant effect. The change of resistance reflects the force status of the structure and its performance mainly depends on the sensitivity of pressure-resistantance. Such composite’s sensitivity has a relationship with the sample preparation process. In this paper, the resin-based carbon fiber is improved so as to obtain a high sensitivity and good stability bundle of modified carbon fiber polymer-matrix composites. Clamp the samples of this material on the micro-tensile test table, the characteristics of mechanism pressure-resistant is analyzed by observing the fiber interface changes through SEM when loaded, combined with monotonic loading curve of the sample. With the electrical model of parallel circuit and normal distribution model and Weibull model, piezoresistivity model is established. Compared with the model curve and the experimental model, the mode is verified being a high accuracy.