Abstract: Based on the characteristic of damage identification for engineering structure, a method of damage identification is put forward. First, with test modal reference the flexibility matrix of structure is set. And by the characterristic of the change in flexibility matrix before and after the damage to the structure, the position of damage in structure is found. Then based on that position, the damage state in structure is idertificated by method of fuzzy pattern recognition. At last, by giving a calculation example of a truss structure, it proves that the method has better stability, better anti-noise, and is much more accurate in identification, so it is very practical in engineerings.