Abstract: The testing methods and contents for a concrete structure factory building after a fire hazard are introduced, including concrete strength,steel strength,carbonation depth in concrete and so on. And by analyzing the testing results, several strengthening schemes were taken. These measures were outer sticking steel plate,external steel_clad method,RC beams section steel adhesion and increasing section method. An instance of construction is given here. The structure completely resumes its bearing capacity after strengthening.