Abstract: Beijing Workers' Stadium was reinforced for the first time in 1986,after long application and effect of temperature stress,there were some cracks on partial inclined beams near the joints of beam and column. For the second reform,external prestressing is used for strengthening the beams. It is introduced the structural system of prestressed concrete members using external prestressing in the inclined beam of the Beijing Workers' Stadium,the principle of determining the prestressing force and the design of the deflector block;as well as the construction process and construction technology. Which shows the superiority of external prestressing strengthening.