To study the seismic behavior of interior joints of high-strength concrete frame structure, 10 interior joints with construction joints of high-strength concrete frame structure are carried out based on the low-cycle loadings test. The influences of the axial compression ratio, concrete strength grade of core area of interior joints, and the length of high-strength concrete in columns and joints extends to beams are studied. Failure characteristics, bearing capacity, displacement ductility and hysteretic curves are also analyzed deeply. Test results show that all of the interior joints are damaged at the end of beam by bending. The lengths of high-strength concrete in columns and joints extension to beams have little effect on yield load, peak load and hysteretic curves as well. While the length of high-strength concrete in columns and joints extensions to beams have significant effect on displacement ductility. On the basis of the test results analysis and construction factors, it is shown that 1.5his the optimal length of high-strength concrete in columns and joints extension to beams.