By mechanical mechanism analysis, confined index was proposed to represent the compressive behavior of confined concrete. According to confined effect, three confined level(high, middle, low) was divided. Based on the test results, the formulas to calculate compressive strength，peak strain, ultimate strain and fracture strain were proposed and verified, a stress strain model of confined concrete was developed. The proposed model can predict the test result accurately and satisfy the damage boundary conditions. The model is feasible in the theoretical analysis and design of this type of member.