In this paper,the low-cycle fatigue fracture crack growth is investigated gropingly for Zr-4 alloy(Zircaloy-4).By analyzing the trend of patulous energy and fractal dimension in the crack growth direction,three stages(A-B,D-E,and F-H) of different energies and fractal dimensions are discovered in the growth period of dynamic crack.The normalized energies are 0~0.0156,0.8754~0.9652,and 1 for the A-B,D-E,and F-H stages,respectively.But for the fractal dimension,it is in the middle for the A-B stage,its mean value and standard deviation in LL and LH directions are 2.2796,0.0277 and 2.4516,0.0592,respectively;and it is minimal for the D-E stage,its mean value and standard deviation in LL and LH directions are 2.2214,0.0131 and 2.3477,0.0550,respectively;it is maximal for the F-H stage with the mean value and standard deviation in LL and LH directions of 2.3414,0.0704 and 2.5398,0.0263,respectively.Finally,the phenomena were studied on the morphology of low-cycle fatigue fracture by SEM for Zircaloy-4.