Abstract: Compression bar is an important structural member in buildings or bridges. When the compression of the bar reaches its critical load, the whole structure will lost the stability. Based on the theory of precise transfer matrix method and the slightly bending differential equation of compression bar, a precise transfer matrix format for buckling analysis of compression bar under axial load was derived. By this method, the critical loads of compression bar with different boundary constraints were calculated, and the calculation result agreed well with the theoretical result, showing that the method was accurate and effective. Examples showed that the amplification of critical loads of center compression bar increases with modes, so the design of center compression bar should avoid the occurrence of low mode buckling.