Activation of lymphatic cells is associated with changes in morphology, ultrastructure and adhesion force. We have investigated the activation efficiency of Staphylococcus aureus (SAC) on B-cell chronic lymphatic leukaemia (B-CLL) cells using atomic force microscopy (AFM), and found changes in the above properties. Cell viability and proliferation were measured using Cell Counting Kit-8 (CCK-8) and enzyme-linked immunosorbent assay (ELISA). AFM clearly showed that the volume and nuclear–cytoplasm ratio of cells increased significantly with activated time. It also showed that pseudopodia and immunological synapses began to appear at 24 h. In the activation process, nano-structures of the cell surface became aggregated, and adhesion increased. In conclusion, the results indicate a close relationship between membrane reconstruction and multiplication process of B-CLL cells.