It is known that radio frequency interference (RFI) degrades the performance of DMT systems for digital subscriber loops. The RFI signal, though narrowband in nature, may be spread to subchannels around the RFI frequencies due to the large sidelobes of the receiving rectangular window. In this paper, we propose a joint consideration of channel shortening and RFI suppression in the design of time domain equalizers (TEQ). We will design the TEQ by minimizing ISI, channel noise and RFI interference. Simulation results are given to show that the proposed method can considerably reduce interference around the RFI frequencies and increase the transmission rate.