Transport and magnetic properties of the CuIr2？xAlxS4 system have been investigated. It is found that the
Peierls-like phase transition is suppressed with the substitution of Al. In addition, the resistivity under
strong magnetic field shows that the Peierls-like phase transition is very steady to the external field. The
study of magnetization reveals that the density of states at the Fermi level [N(EF )] is not influenced by
the doping of Al, while the localization length is decreased with the increase of Al. Theoretically, we find
that the upturn of the magnetization at low temperatures is produced by paramagnetic clusters, which
are formed by several moments captured by defects. Moreover, the increase of Al content just increases
the number of capture centers, but does not affect the magnetic moment of a single paramagnetic cluster.