Abstract: The structure and phase content in industrial catalyst NiO/α-Al_2O_3 before and after reaction were studied by EXAFS. Part of NiO in the catalyst is reduced to Ni phase. The reducing amount is different for the samples located at different height of the reactor. The phase contents of NiO and Ni were measured and the local structure around Ni atoms was measured by using mixed phase EXAFS analysis method. The results show that the average coordination number of Ni atom in Ni phase is decreased compared with metal Ni. This is caused by more Ni atoms located at surface state. The dimension of Ni cluster is estimated. Meanwhile there is no obvious change of the environment of Ni atom in NiO phase before and after reaction.