The forced translocation of diblock copolymers (A(NA)BNB) through compound channels composed of part a with length La near the cis side and part beta with length L-beta near the trans side was investigated. The interaction between monomer A and channel alpha is strongly attractive, while all other interactions are purely repulsive. We study the translocation mode that the block A threads the channel ahead of the block B since it is the most probable translocation event. Simulation results show that the translocation process is remarkably dependent on L-alpha and there are two maxima of translocation time. The physical mechanisms are discussed from the free energy landscape of polymer translocation. The place of the first maximum, at which there is a deepest free energy well before the block A completely enters the channel, is independent of NA. The place of the second one is at N(A)b(x) with b(x) the mean bond length along the channel, resulted from the matching of block A with channel a. Results show that the translocation time of diblock copolymer can be tuned by using compound channels.