An inlet guide vane assembly of a gas turbine, wherein the gas turbine comprises an inner inlet casing and an outer inlet casing, the outer inlet casing is sheathed outside the inner inlet casing, the outer inlet casing comprises a cylindrical fixing part, and the inlet guide vane assembly comprises: a plurality of inlet guide vanes, one end of each of the inlet guide vanes being rotatably connected to a first fixing part, each of the inlet guide vanes being rotatable in a radial direction of the fixing part, each of the inlet guide vanes comprising a fixing shaft, and the fixing shaft being disposed at the end away from the fixing part; and a fixing assembly comprising: a support ring capable of being coaxially fixed to the inner inlet casing with the fixing part, wherein the support ring comprises a support part formed by radially extending from an outer surface of the support ring, and the support part comprises a support wall facing towards the inner inlet casing, characterized in having a fixing ring sheathed on the outer surface of the support ring and located between the inner inlet casing and the support part, wherein the fixing ring comprises a fixing wall facing towards the support part, the fixing wall is able to form, in cooperation with the support wall, a plurality of accommodating cavities corresponding to the plurality of inlet guide vanes after making contact with the support wall, and the fixing shafts are rotatably inserted into the accommodating cavities, and an abutting member disposed between the inner inlet casing and the fixing ring in an axial direction of the support ring, wherein the abutting member is in interference fit with the inner inlet casing and the fixing ring. a plurality of inlet guide vanes, one end of each of the inlet guide vanes being rotatably connected to a first fixing part, each of the inlet guide vanes being rotatable in a radial direction of the fixing part, each of the inlet guide vanes comprising a fixing shaft, and the fixing shaft being disposed at the end away from the fixing part; and a fixing assembly comprising: a support ring capable of being coaxially fixed to the inner inlet casing with the fixing part, wherein the support ring comprises a support part formed by radially extending from an outer surface of the support ring, and the support part comprises a support wall facing towards the inner inlet casing, characterized in having a fixing ring sheathed on the outer surface of the support ring and located between the inner inlet casing and the support part, wherein the fixing ring comprises a fixing wall facing towards the support part, the fixing wall is able to form, in cooperation with the support wall, a plurality of accommodating cavities corresponding to the plurality of inlet guide vanes after making contact with the support wall, and the fixing shafts are rotatably inserted into the accommodating cavities, and an abutting member disposed between the inner inlet casing and the fixing ring in an axial direction of the support ring, wherein the abutting member is in interference fit with the inner inlet casing and the fixing ring. a support ring capable of being coaxially fixed to the inner inlet casing with the fixing part, wherein the support ring comprises a support part formed by radially extending from an outer surface of the support ring, and the support part comprises a support wall facing towards the inner inlet casing, characterized in having a fixing ring sheathed on the outer surface of the support ring and located between the inner inlet casing and the support part, wherein the fixing ring comprises a fixing wall facing towards the support part, the fixing wall is able to form, in cooperation with the support wall, a plurality of accommodating cavities corresponding to the plurality of inlet guide vanes after making contact with the support wall, and the fixing shafts are rotatably inserted into the accommodating cavities, and an abutting member disposed between the inner inlet casing and the fixing ring in an axial direction of the support ring, wherein the abutting member is in interference fit with the inner inlet casing and the fixing ring.