Abstract: The composite masonry of thermal-insulating lightweight concrete hollow block is a new type of structure with composite polystyrene(EPS) soil as its inner core and the lightweight concrete block as its external mould, because it makes the heat preservation and antiseism as a whole, so it suits to town building.In this paper, based on the experiment of 9 groups and 27 shear specimens, the laws of anti-shearing intensity and shear failure mechanism of the composite block masonry were analysed, it was analyzed the effects of different mixture proportions of inner core strength, different grouting ratio and different mortar strength on the shearing strength of composite block masonry.Meanwhile 1 group of shear specimens of baked brick and concrete perforated brick were made to compared with the new composite block;the results show that inner core strength is a major influence factor for masonry shearing strength, and mortar strength is weak for masonry shearing strength, at the same time, inner core strength is about 71% contribution for masonry shearing strength.In the end, the shearing intensity of the composite block masonry was higher than the soil brick and concrete porous brick.