The structure relaxation of Zr5555Cu3030Al1010Ni55 bulk amorphous alloy annealed at 340℃ for different times have been investigated by synchrotron radiation small angle x-ray scattering and differential scanning calorimetr y. Annealing time dependence of electronic density fluctuation in the amorphous alloy and apparent activation energies for the enthalpy relaxation were presente d and discussed. The experimental results show that electronic density fluctuati ons increase first and then decrease with increasing annealing time, while the a pparent activation energy for the enthalpy relaxation exhibits an opposite chang e, i.e., decreases first and then increases. Both indicate the transformatio n from the liquid-like region to the solid-like region in amorphous alloy duri ng annealing.