  We calculated the branch ratios of $\Lambda_C\to \Lambda K$ and $\Lambda_C\to
\Lambda \pi$ within factorization approximation. It is found that the results
suffers from the uncertainties of form factors. To reduce such uncertainties,
we checked the ratio of the two channels, which is obtained as $R=0.0743\pm
0.0014$. It is found that the uncertainty caused by form factors is
significantly reduced. This note is prepared for the BESIII collaboration.
