  We report the effects of Al-doping on the structure and magnetic properties
in CaBa(Co$_{1-x}$Al$_{x}$)$_4$O$_7$ (0$\leq$x$\leq$0.25). The system exhibits
a structural transition from an orthorhombic symmetry to a hexagonal symmetry
when the Al content exceeds $x =$ 0.1. The Curie temperature and the value of
the magnetization decrease with increasing Al doping level, indicating that the
ferrimagnetic ground state is gradually suppressed. The ground state eventually
transits into a spin-glass state for $x >$ 0.1. Moreover, the short-range
magnetic correlations, which occur at high temperatures in CaBaCo$_4$O$_7$, are
found to be gradually suppressed with increasing Al content and eventually
disappear for $x =$ 0.25. By comparing our results with other Co-site doping
cases, we suggest that the lattice and the spin degrees of freedom are
relatively decoupled in CaBaCo$_4$O$_7$.
