The changes of hydrogen bond structures and the ion association of (NH4)2SO4 aqueous solution with different mass fractions at room temperature are investigated by Raman spectroscopy and excess Raman spectroscopy. The stretching vibration interval of O-H at 2800-4000 cm -1 and holosymmetric stretching vibration interval of S O42- at 940-1020 cm -1 are studied. The peak splitting of Raman data are handled, and positive and negative peaks integral areas of excess Raman spectra are analyzed. The results show that the mass fraction of 12.00% is the turning point of the hydrogen bond structures and the ion association in the solution. When the mass fraction is greater than 12.00%, the hydrogen bond structures of DDA type and DAA type increase, and the hydrogen bond structures of DDAA type and DA type as well as free OH decrease. The existence of ion pairs changes in the solution and N H4+ forms contact ion pairs with S O42-.