  We present our optical multicolor photometry for the nearby cluster of
galaxies Abell 2255 with 13 intermediate filters in the BATC system. The
spectral energy distributions (SEDs) in the optical band for more than 7000
sources are achieved down to V ~ 20 in a field of 58' x 58' centered on this
rich cluster. Abell 2255 has been recently observed by the SDSS. A method of
combining the SDSS photometric data in five broad bands and the BATC SEDs is
then explored. The application of the technique of photometric redshift shows
that the combined SEDs with higher resolution could lead to a more accurate
estimate of photometric redshift. Based on 214 spectroscopically confirmed
member galaxies, the bimodality and large dispersion in the velocity
distribution indicate that Abell 2255 is an unrelaxed system. A tight
color-magnitude correlation for 188 known early-type cluster galaxies is found.
After an exclusion of 254 extragalactic sources with known redshifts, the
combined SEDs for 2522 galaxies allow a further membership selection by the
photometric redshift technique and color-magnitude correlation. As a result,
313 galaxies with their photometric redshifts between 0.068 and 0.090 are
selected as new cluster members. The combined SEDs and estimated redshifts for
previously known and newly-selected member galaxies are cataloged. On the basis
of the enlarged sample of member galaxies, the spatial distribution, localized
velocity structure, color-magnitude relation, and luminosity function of
cluster galaxies are discussed. The reverse peculiar velocities are found for
two satellite subclusters located on opposite sides of the central
concentration, which supports an ongoing merger in Abell 2255.
