Abstract: A 3-story frame structure was put into operation in 2002 and was on fire in september 2012，because the short-circuit of aged wire belong to the car wash located in the underground parking． The main burned area was about 180 m2 during the 2. 5 h． Above the burned area is the roof parking ramp-way of the large supermarket． In order to assure the safety of the whole structure，the reinforced concrete beam，column and slab after fire were test on-site and the structure was checking-calculated through the PKPM software by the presumption strength． According to comparison of the reinforced methods and analysis of the checking calculated results，the enlargement section， embedded steel bars and grouting materials perfusion were adopted to strengthen the frame structure． There is no cracks and deformation in the structure until now． Which shows that the reinforced mode is reasonable and the enhancement effect is good．