Abstract: Investigations of high-pressure structure and equation of state of LiAlO2 have been conducted in diamond anvil cell with silicon oil as pressure medium by aid of synchronous radiation angle dispersion X-ray diffraction method.It is found that LiAlO2 is of a tetragonal structure under ambient pressure, and the phase transition from tetragonal structure to unknown structure occurs at 9.8 GPa.The new structure remains stable until the highest pressure of 26.6 GPa comes.Because of the broadening of diffraction peaks, new structures can not be solved.By fixing the first-order derivative of bulk modulus at 4, the bulk modulus of 120.6 (3.2) GPa is obtained from the tetragonal structure fitting in 0-7.6 GPa.The result is different from reported value, which needs further verification.