Abstract Binary stars are common in star clusters and galaxies, but the detailed effects
of binary evolution are not taken into account in some color-magnitude diagram
(CMD) studies. This paper studies the CMDs of twelve globular clusters via binarystar
stellar populations. The observational CMDs of the star clusters are compared to
those of binary-star populations, and then the stellar metallicities, ages, distances and
reddenings of these star clusters are obtained. The paper also tests the different effects
of binary and single stars on CMD studies. It is shown that binaries can better fit the
observational CMDs of the sample globular clusters compared to single stars. This
suggests that the effects of binary evolution should be considered when modeling the
CMDs and stellar populations of star clusters and galaxies.