In reinforced concrete (RC) flat slabs, punching shear may cause brittle failures at slabcolumn edge connections. This may be attributed to insufficient punching strength due to essential works such as changing of building use and construction or design errors. An experimental test program of thirteen RC flat slab-edge column connections was prepared and specimens were tested. The first specimen was not strengthened and considered as a control specimen. Six specimens were strengthened without preloading; three specimens were strengthened with one row of stirrups around the edge column at the three sides made from Glass Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP) and steel links. The other three specimens were strengthened with two rows of stirrups. Another six specimens were repaired. They were subjected first to 0.75 of ultimate failure load of the control specimen Pu before repairing.; three specimens were repaired with one row of stirrups around the edge column made from GFRP, CFRP and steel links and the other three specimens were repaired with two external rows of stirrups. The behaviors of the tested specimens were compared. The experimental results showed an increase in punching shear resistance for strengthened and repaired specimens. A computer program based on nonlinear finite element of three dimensional isoparametric brick elements were used. Each element has 20 nodes and each node has three degrees of freedom. The reinforcements are represented by embedded reinforcing bars and strengthening rods. The nonlinear analysis includes the stress strain relationships, crushing, propagation of cracks, and tension stiffening effects. The finite element results are compared with the experimental results. The main conclusions drawn from the study are discussed and summarized. Carbon fiber stirrups showed the best results. The results of the finite element analysis showed a good harmony with the experimental results.