  Doubly Cabibbo-suppressed (DCS) nonleptonic weak decays of antitriplet
charmed baryons are studied systematically in this work. The factorizable and
nonfactorizable contributions can be classified explicitly in the
topological-diagram approach and treated separately. In particular, the
evaluation of nonfactorizable terms is based on the pole model in conjunction
with current algebra. All three types of relevant non-perturbative parameters
contributing factorizable and nonfactorizable terms are estimated in the MIT
bag model. Branching fractions of all the DCS decays are predicted to be of
order $10^{-4}\sim 10^{-6}$. In particular, we find that the three modes
$\Xi_c^+\to \Sigma^+ K^0, \Sigma^0 K^+$ and $\Xi_c^0\to \Sigma^- K^+$ are as
large as $(1\sim 2)\times 10^{-4}$, which are the most promising DCS channels
to be measured. We also point out that the two DCS modes $\Xi_c^+\to \Sigma^+
K^0$ and $\Xi_c^0\to \Sigma^0 K^0$ are possible to be distinguished from
$\Xi_c^+\to \Sigma^+ K_S$ and $\Xi_c^0\to \Sigma^0 K_S$. The decay asymmetries
for all the channels with a kaon in their final states are found to be large in
magnitude and negative in sign.
