The friction that occur between arch wire and the brackets during arch wire sliding in fixed orthodontic appliance will affect negatively on the outcome of the orthodontic treatment in addition to the treatment time. The process of friction is a critical issue and should be understood properly by the orthodontist in order to provide the optimum treatment result in a short period of time. Aim: The aim of our study was to compare the effect of calcium carbonate air abrasive on static friction and micromorphology of bracket slot surface for two different stainless steel self-ligated brackets. Methods: 120 passive stainless steel self-ligated brackets from two different commercial brands where involved in the study (discovery® sl2.0, Dentaurum co. and Damon®, Ormco co.). The samples were divided randomly into 8 groups, and every group with 5 samples, the criteria for classification of these groups depend on bracket types and air abrasion periods. Round (18 inches) NITI arch wire was used to slide through 3 brackets with the middle one 1 mm higher than the others, the distance of sliding through the brackets was 10 mm, the machine used for measurement included the (instron) universal testing machine, the roughness of the bracket slot surface was analyzed be the machine of (scanning electron microscope). Results: The effect of air abrasive agent calcium carbonate on the both types of metal self-ligated brackets result in elevation the amount of static friction for (discovery® l2.0 by 35.157%, Damon® by 36.652%). Viewing the slot of the brackets under microscope by using (SEM) device reveal great modification in surface of the slot with uneven and rougher surface when compared to the brackets of control group that appear with polished and smooth surface.