Abstract: Quasi-static tensile tests at room temperature were carried out on Q235B steel, 45 steel and T8 steel. The strain and radius at necking as well as strain distribution during tension were determined by a three-dimensional digital image correlation (3D-DIC) method, and were compared with the results obtained by force-displacement sensor measurement and ABAQUS finite element simulation. The results show that the strain and radius at necking of the three carbon steels in tension showed a slow first and then fast change trend, which was consistent with the tensile deformation behavior of carbon steels. The change law of strains in stretching was consistent with the finite element simulation results; the average relative error was less than 2.35%. The average relative error of strains obtained by the 3D-DIC method and by the force-displacement sensor test was 0.003%, indicating the 3D-DIC method was accurate. The distribution of strains along the x-axis and y-axis directions obtained by the 3D-DIC method was in good agreement with the finite element simulation results, but the finite element simulation was more more precise. For the strain distribution on the xy plane, the results obtained by the two methods were quite different.