A steering mechanism of an all-terrain vehicle, comprising: a steering shaft ; a power steering system ; and a connecting portion comprising a first shaft sleeve , a second shaft sleeve , and an elastic membrane assembly , wherein the elastic membrane assembly comprises at least one elastic membrane ; the first shaft sleeve and the second shaft sleeve are arranged on two sides of the elastic membrane assembly and fastened to the elastic membrane assembly ; an end of the first shaft sleeve away from the elastic membrane assembly is coupled to the steering shaft , and an end of the second shaft sleeve away from the elastic membrane assembly is coupled to the power steering system , wherein the power steering system is splined to the second shaft sleeve . wherein the power steering system comprises a connecting shaft having an external spline , the second shaft sleeve is provided with a shaft hole having an internal spline , and the internal spline is arranged on an inner wall of the shaft hole ; and the second shaft sleeve is fitted over the connecting shaft, and the external spline is fitted with the internal spline , wherein the second shaft sleeve comprises a second body having the shaft hole , and a mounting portion arranged on an outer wall of the second body ; characterized in that the mounting portion comprises a first mounting block and a second mounting block arranged oppositely, and a gap in communication with the shaft hole is formed between the first mounting block and the second mounting block ; and the second body is fitted over the connecting shaft, and the first mounting block is fastened to the second mounting block . a steering shaft ; a power steering system ; and a connecting portion comprising a first shaft sleeve , a second shaft sleeve , and an elastic membrane assembly , wherein the elastic membrane assembly comprises at least one elastic membrane ; the first shaft sleeve and the second shaft sleeve are arranged on two sides of the elastic membrane assembly and fastened to the elastic membrane assembly ; an end of the first shaft sleeve away from the elastic membrane assembly is coupled to the steering shaft , and an end of the second shaft sleeve away from the elastic membrane assembly is coupled to the power steering system , wherein the power steering system is splined to the second shaft sleeve . wherein the power steering system comprises a connecting shaft having an external spline , the second shaft sleeve is provided with a shaft hole having an internal spline , and the internal spline is arranged on an inner wall of the shaft hole ; and the second shaft sleeve is fitted over the connecting shaft, and the external spline is fitted with the internal spline , wherein the second shaft sleeve comprises a second body having the shaft hole , and a mounting portion arranged on an outer wall of the second body ; characterized in that the mounting portion comprises a first mounting block and a second mounting block arranged oppositely, and a gap in communication with the shaft hole is formed between the first mounting block and the second mounting block ; and the second body is fitted over the connecting shaft, and the first mounting block is fastened to the second mounting block . <EOS>