Through the experiments of 12 (6 half-grouted and 6 full-grouted) compressive specimens, the failure pattern and the ultimate capacity of concrete block masonry were analyzed. Test results showed that the compressive strength and the elastic modulus of two ends opened block masonry were enhanced compared to the common concrete block masonry (like K-block). Based on the compression mechanism of two ends opened block masonry, a semi-empirical theory formula was presented for grouted two ends opened block masonry. And the calculation results with the formulas were in good agreement with the test results. 