Considering the problem that channel steel insertion is easy to cause bending instability, a structural measure of setting batten along the channel steel is proposed. Based on the spatial coordination method, a theory of the stiffening effect of the batten was proposed, and the overall stability calculation method of channel steel axial compression member with batten was deduced. It provides a theoretical basis for local reinforcement optimization design of open channel steel in engineering. Numerical examples show that this method can effectively quantify the position effect and size effect of the plate. The regularity of stable critical load of the number and width of the plate, arrangement mode and length of the member is analyzed. The calculated results are basically reasonable and verify the application effect of practical engineering.