Abstract: Five frame joints strengthened by self-compacting concrete and one integral casting joint for comparison were prepared. Static tests using MTS servo loading system were carried out to these joints under secondary loads to study the influence of 4 different interface treatments on the seismic performance. Interface treatments of the five strengthened specimens were chiseling-grossness, cutting groove with different groove density, combination of chiseling and cutting groove, and combination of chiseling and planting short reinforced bars The results of damage process, strains of both the old steel and new steel and the load-displacement hysteresis loops were obtained. It is found that all the four interface treatments can improve the co-operational performance of the old concrete and new concrete, and the ultimate strength, displacement and displacement ductility coefficient of the strengthened joints by the combination of chiseling and cutting groove or the combination of chiseling and planting short reinforced bars are larger than those by chiseling only, and as for the ultimate capacity, the strengthened joints with each of the 4 treatments was close to the integral contrast casting joint.