The electrophoretical stretching of DNA in a hybrid microchannel is analyzed in this paper. The channel comprises a large insulating cylinder and a hyperbolic contraction that can cause the DNA deformation. Brownian dynamics simulation is used to characterize the dynamical stretching process of a long T4 DNA in hybrid microchannels. The computational results show us the larger average extension of DNA in cylinder-hybridized microchannels than that in the single microcontractions due to the prestretched effect of cylinder on DNA. Moreover, the location and the radius of the insulating cylinder in hybrid microchannels have great effects on the stretching behavior of DNA. (C) 2009 Elsevier Ltd. All rights reserved.