Abstract: In order to investigate the in-plane compressive failure mechanisms for isosceles-trapezoid honeycomb core of glass steel sandwich panels, the testing measurement on in-plane compressive properties of sandwich panel were conducted by material testing machine, and simulated investigation were carried out. The results show that the in-plane compressive damage ways of sandwich panels have three types of panel breaking, buckling instability of sandwich panel and deboning between panel and honeycomb core in sandwich panel. Panel is the main load bearing component of sandwich panel in-plane compression, and the honeycomb core function by clamped effect to the panel. The structural parameters and material parameters of panel are the main factors which influence the compressive strength and compressive rigidity for in-plane compression of sandwich panels. The structural parameters and material parameters of majority honeycomb core have little influence on compressive strength for in-plane compression of sandwich panels, but the structural parameters of individual honeycomb core have relatively remarkable influences on compressive rigidity for in-plane compression of sandwich panels. When the volume of sandwich panel is constant, the compressive strength and compressive rigidity for in-plane compression of sandwich panels increase gradually with honeycomb core unit cell body number increasing.