  We propose a realization of perfect valley filters based on the chiral
domain-wall channels between a quantum anomalous Hall insulator and a quantum
valley Hall insulator. Uniquely, all these channels reside in the same valley
and propagate unidirectionally, $100\%$ valley-polarizing passing-by carriers
without backscattering. The valley index, the chirality, and the number of the
channels are protected by topological charges, controllable by external fields,
and detectable by circular dichroism.
