In situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source has been used to investigated the free volume change in Ni77P23 amorphous alloy up to 30.5 GPa at room temperature in a diamond-anvil cell. The atomic configuration information such as coordination number and atomic spacing was derived by radial distribution function via Fourier transformation. The results show that in the pressure range of 0—30.5 GPa, the structure of Ni77P23 amorphous alloy is stable. The compression behavior is investigated using in-situ high pressure measurment. The equation of state -ΔV/V0=0.08606P-3.2×10-4P2+5.7×10-6P3 is determined by fitting the experimental data according to the Bridgman equation.