  We have carried out a detailed binary populations synthesis (BPS) study of
the formation of subdwarf B (sdB) stars and related objects (sdO, sdOB stars)
using the latest version of the BPS code developed by Han et al.(1994, 1995a,
1995b, 1998, 2001). We systematically investigate the importance of the five
main evolutionary channels in which the sdB stars form after one or two
common-envelope (CE) phases, one or two phases of stable Roche-lobe overflow
(RLOF) or as the result of the merger of two helium white dwarfs (WD) (see Han
et al. 2002, Paper I). Our best BPS model can satisfactorily explain the main
observational characteristics of sdB stars, in particular their distributions
in the orbital period - minimum companion mass diagram and in the effective
temperature - surface gravity diagram, their distributions of orbital period,
log (g theta^4), and mass function, their binary fraction and the fraction of
sdB binaries with WD companions, their birthrates and their space density. We
obtain a Galactic formation rate, a total number in the Galaxy, the intrinsic
binary fraction for sdB stars. We also predict a distribution of masses for sdB
stars that is wider than is commonly assumed and that some sdB stars have
companions of spectral type as early as B. The percentage of A type stars with
sdB companions can in principle be used to constrain some of the important
parameters in the binary evolution model. We conclude that (a) the first RLOF
phase needs to be more stable than is commonly assumed; (b) mass transfer in
the first stable RLOF phase is non-conservative, and the mass lost from the
system takes away a specific angular momentum similar to that of the system;
(c) common-envelope ejection is very efficient.
