A positive integer is called a congruent number if it is the area of a right-angled triangle with rational side-lengthes. For example,  Fermat proved that 1, 2, 3 are not congruent and Fibonacci proved that 5, 6, 7 are congruent. Congruent number problem is to determine whether a given positive integer is congruent.  The problem is closely related to the Birch and Swinnerton-Dyer conjecture for elliptic curves. In this talk, I will report some progress on this problem.