  Within the mean-field theory, we investigate the magnetic properties of a
charged spin-1 Bose gas in two dimension. In this system the diamagnetism
competes with paramagnetism, where Lande-factor $g$ is introduced to describe
the strength of the paramagnetic effect. The system presents a crossover from
diamagnetism to paramagnetism with the increasing of Lande-factor. The critical
value of the Lande-factor, $g_{c}$, is discussed as a function of the
temperature and magnetic field. We get the same value of $g_{c}$ both in the
low temperature and strong magnetic field limit. Our results also show that in
very weak magnetic field no condensation happens in the two dimensional charged
spin-1 Bose gas.
