An enclosed-channel reactor system is provided, which includes: a reactor body having a plurality of enclosed channels therein; an upper cap disposed at one end of the reactor body and having an inlet port communicating with the plurality of enclosed channels; a lower cap disposed at the other end of the reactor body opposite to the upper cap and having an outlet port communicating with the plurality of enclosed channels; and at least a conduit plate disposed between the upper cap and the reactor body for guiding a precursor injected from the inlet port into the plurality of enclosed channels uniformly.