Strengthening and repairing of reinforced concrete beams by using thin fibers concrete jacket have many advantages such as increasing of ultimate load, enhancement of serviceability limit state, resistance to fire and avoiding of corrosion problems that appear in steel plate jacket. The present work conducted to study the strengthening and repairing of reinforced concrete beams subjected to short time repeated load by using mixed steel fibers concrete jacket (MSFCJ). For this purpose fourteen reinforced concrete beams have a cross section 120x300 mm, total length 2300 mm were fabricated and tested under three point load. The used concrete mix contains two mixed shape steel fibers, corrugated and end-hooked steel fibers. Two of these beams were fabricated without strengthening, the first was tested under static load up to failure and the second was tested under short time repeated loads up to failure. The rest twelve beams, six of them were strengthened by U-shape MSFCJ with various thickness and steel fibers content while the other six beams were loaded up to 0.5 the ultimate static load and then repaired using MSFCJ. The twelve beams were tested under short time repeated load. The tests results showed the effectiveness of the proposed technique in both ultimate and serviceability limit state.