We report a new density functional theory (DFT) for block copolymers and its performance for representing the microscopic structure has been tested with the configurational-bias Monte Carlo simulation. The segmental density profiles are calculated for systems containing short block copolymers. represented by tangent-sphere square-well chains of sequences "AABK", "AAAABBBB", "ABBBBA". "ABBBBBBA", "BBAABB", and "BBBBAABBBB" confined in slit pores where the planar surfaces attract "A" segments but repel "B" segments. The detailed segmental density profiles are calculated for block copolymers confined in slit pores where the planar surfaces attract A segments but repel B segments. For all conditions considered, the microscopic structures predicted by the DFT are in excellent agreement with the simulation results. Interesting loop and tail conformations of the block copolymers are observed near the selective surfaces. The effects of surface energy, chain length. and copolymer backbone Structure's on the microscopic segregation of "AB" segments are also investigated.