  We compare six popularly used evolutionary population synthesis (EPS) models
(BC03, CB07, Ma05, GALEV, GRASIL, Vazdekis/Miles) through fitting the full
optical spectra of six representative types of galaxies (star-forming and
composite galaxies, Seyfert 2s, LINERs, E+A and early-type galaxies), which are
taken from the Sloan Digital Sky Survey (SDSS). Throughout our paper, we use
the simple stellar populations (SSPs) from each EPS model and the software
STARLIGHT to do our fits. Our main results are: Using different EPS models the
resulted numerical values of contributed light fractions change obviously, even
though the dominant populations are consistent. The stellar population
synthesis does depend on the selection of age and metallicity, while it does
not depend on the stellar evolution track much. The importance of young
populations decreases from star-forming, composite, Seyfert 2, LINER to
early-type galaxies, and E+A galaxies lie between composite galaxies and
Seyfert 2s in most cases. We conclude that different EPS models do derive
different stellar populations, so that it is not reasonable to directly compare
stellar populations estimated from different EPS models. To get reliable
results, we should use the same EPS model for the compared samples.
