Stone masonry with micro-aggregate concrete joints has been widely used in long span arch bridges in China. However, the mechanical properties of this kind of high-strength masonry have been seldom studied. This paper presents compressive strength test study of eight groups of masonry specimens, which consist of C30 or C40 micro-aggregate concrete joints and five kinds of dressed stone blocks. The masonry mechanical behavior is described and test results are analyzed. An empiric formula of the masonry compressive strength is obtained. Finally, design value of masonry compressive strength is assessed and discussed.