Abstract: According to the measurement method of precision instrumentation radar's orthogonal axis precision, two kinds of pedestal structure are analyzed. Based on the structures' characteristics, the two measurement methods of radar's orthogonal shafting precision are compared, and a new virtual location measurement method is proposed which is focused on Y-shape pedestal. A virtual common axis paralleled to the elevation axis and the ground is established with auto-collimator and reticule, the axis deviation between the elevation axis of antenna pedestal and the virtual common axis is measured, then obtain the precision of radar's orthogonal axis precision.