[Objective] To study the division of Rhodococcus sp. R04 cells and the effect of biphenyl on cellular morphology and cell division. [Methods] Using fluorescence microscopy, scanning electron microscopy and transmission electron microscopy, we analyzed the division of R. R04 cells cultured under different conditions. [Results] Rhodococcus sp. R04 exhibited asymmetric and symmetric division, and the proportion of the two types of division was about 7:3. The culture conditions did not affect the proportion of asymmetric division cells. The septum was located on the center to the poles, with some clustering at 30% and 50% of the cell length. Rhodococcus sp. R04 degraded biphenyl, but its division would be inhibited by biphenyl. Microscopic observation showed that Rhodococcus sp. R04 cells formed filaments and exhibited abnormal division in early exponential phase under biphenyl culture conditions. As the culture time was prolonged, the cells finally restored normal division. [Conclusion] Biphenyl/polychlorinated biphenyl has a strong effect on the reproduction and growth of Rhodococcus sp. R04 cell, but it does not affect the mode of cell division.