An apparatus for channel interference cancellation includes a first interference-cancellation module and a first cancellation-signal generating circuit. The first interference-cancellation module comprises a first processing circuit including a grouping circuit and a first transforming circuit. The grouping circuit divides received data into a plurality of groups of first sub-data. The first transforming circuit sequentially transforms the groups of first sub-data from a first domain to a second domain to generate a plurality of groups of first transformed sub-data. The first cancellation-signal generating circuit comprises a delay unit, a first processing unit and a second processing unit. The delay unit sequentially delays the groups of first transformed sub-data to generate a plurality of groups of delayed sub-data. The first and the second processing unit output a first and a second processed signal according to the groups of first transformed sub-data and the groups of delayed sub-data respectively.