Side-pressure laminated bamboo lumber is made by gluing and pressing bamboo sheets together and can be used as a structural building material. The experiment and theoretical analysis are carried out for the side-pressure laminated bamboo lumber columns under axial compression in order to understand its performance under axial compression. In the experiment, the curve of load and lateral displacement in the middle of columns with different slenderness ratios is obtained under axial compression by considering the slenderness ratio (range: 23.1–92.4) of the specimen as a variable. Results show that the specimen undergoes an elastic stage, elastic-plastic stage, and failure stage when subjected to stress. The failure is characterized by a prominent ductility during this period. With an increase in the slenderness ratio, the elastic stage for the specimen is shortened, while the elastic-plastic stage is extended. Based on the geometric non-linear analysis, the pressure bar stability is analyzed for the specimen through the large deflection theory. A stable differential equation of the side-pressure laminated bamboo lumber column is established under axial compression. Based on the differential equation, the relationship between the bearing capacity of the axial center of the side-pressure laminated bamboo lumber column under axial compression and the lateral displacement in the middle of column can be derived as the reference for the application of side-pressure laminated bamboo lumber.