The microchannel refers to structural channel of minerals with sperture from 0.3 nm to 2.0 nm. The microtunnel with K filling constructed by active Mn—O octahedron in cryptomelane is quite similar to that with Na and Ca fillings constructed by Si—O and Al—O tetragonal molecular sieve in zeolite. They have the function of molecular sieve. Here the author points out that ultra-microchannel of natural minerals has aperture below 0.3 nm. Most natural minerals with ultra-microchannel structures have the features of ion exchanges among geomaterials. The ultra-microchannel of feldspar that is half of the mass of the crust has been ignored due to its aperture being too small to understand. However, the author's recent experimental research work shows that feldspar has certain ion exchange functions and channel structure features under high or low temperature conditions. At higher temperature Na+ can go into the channel of feldspars. The content of Na2O in feldspar increases up to 15.9 percent. At medium temperature Pb2+ can also enter the channel of feldspar with functions of ion exchange and lead to the formation of Pb-feldspar. At room temperature about 97.94% Cd2+ can be removed by feldspar and hence Cd-feldspar occurs. The effects of typical ultra-microchannel of feldspar are helpful to treat heavy metal pollution and dispose nucleus waste. The ultra-microchannel of natural minerals has played a special role in migration and exchange of geomaterials. The molecular sieves of the microchannel of handful natural minerals have the function of purifying molecular gas pollution, whereas the ionic sieves of ultra-microchannel of most natural minerals are likely to purify ionic water contaminates.