Abstract: In order to investigate the compressive strength for drilling core with different treatments on ends, 12 groups of specimens are proposed. Effects on the compressive strength of core samples, due to different diameters and different strength classes are analyzed. The results show that the testing strength of cores by grinded with ratio 1∶1 is almost the same to that of standard cubic ones curing in similar conditions. This data provide the theoretical background for local Code DG/TJ 08-2020—2007. Based on tests of these specimens, the numerical analysis about the conversion value of compressive strength and factors according to the treatments of the ends are put forward.