A PDMS microchannel mimicking the capillary blood vessel is fabricated by the soft lithography. With treating the PDMS microchannels by different plasmas, the corresponding surface roughness RA data are experimentally measured. Using these PDMS microchannels well defined by proper RA values, liquid streams with microbeads and living HepG2 tumor cells are filled in, respectively. The microbead and cell attachment areas in the PDMS microchannel have been recorded dynamically with 10 min interval. Finally, the author qualitatively discusses the surface roughness effect on the particle or cell attachment in a PDMS microchannel.