  The Internal Linear Combination (ILC) is widely used to extract the cosmic
microwave background (CMB) signal from multi-frequency observation maps,
especially for Satellite experiments with quasi-full sky coverage. We extend
ILC method to CMB polarization map analysis with a small sky patch which is
especially typical for ground-based experiments, by combing ILC with a template
cleaning method which can give pure $B$ map free from $EB$ leakage caused by
partial sky coverage. The feature of our methods is that we do the ILC analysis
on pseudo-scalar $B$ maps, and the advantage is that it totally avoids the
impact of $EB$ leakage on ILC, so that it can improve the efficiency of
component separation dramatically. We demonstrate our methods with mock data of
a future ground-based experiment with a deep survey on a clean patch in the
northern sky, and the results show that the level of foreground residual can be
well controlled, it biases the tensor to scalar ratio ($r$) at the order of
$10^{-3}$ which is comparable to the statistical error by noise.
