  Recent experimental discovery of several families of kagome-lattice materials
has boosted the interest in electronic correlations on kagome lattice. As an
initial step to understand the observed complex phenomena, it is helpful to
know the correspondence between simple forms of interactions and the induced
correlated states on kagome lattice. Considering the lack of such studies, here
we systematically investigate the attractive kagome-lattice Hubbard model using
the mean-field approach and determinant quantum Monte Carlo (DQMC). A
charge-density-wave order satisfying the triangle rule is predicted by the
mean-field treatment, and subsequent DQMC simulations provide indirect evidence
for its existence. The $s$-wave superconductivity is found to be stabilized at
low temperatures, and exists in dome regions of the phase diagrams. We then
determine the superconducting critical temperature quantitatively by
finite-size scaling of the pair structure factor. These results may be helpful
in understanding the observed superconductivity in kagome-lattice materials.
