According to the studies of Li & Han (2008) and Li & Han (2009), binary evolution can affect
the integrated features of populations. Besides the widening of isochrones, binary evolution can
explain some special stars such as blue stragglers in star clusters. It can also interpret the UV excess
in elliptical galaxies (see, e.g., Han et al. 2007). Therefore, it is proposed to use CMD studies on
the basis of some stellar populations that have taken the detailed effects of binary evolution into
account. If the effects of binary evolution are taken into account, some different properties of star
clusters may be obtained. This is helpful for the further understanding of star clusters. In addition,
because a stellar isochrone is a basic ingredient to build stellar populations, comparing the CMDs
of star clusters with the synthetic CMDs of binaries can help us to model stellar populations in
more advanced ways. This paper aims to study the CMDs of a few star clusters via binary stars, and
then compare the results determined by binary- and single-star simple stellar populations (bsSSPs
and ssSSPs). Because globular clusters (GCs) are usually thought to be simple systems that include
metal-poor and old stars, we take some GCs as the star cluster sample of this study.