Objective: To detect 3-dimensional images of anti-N-methyl-D-aspartate receptor Nr1 (NMDAr1) polycolonal IgG affixed on mica in physiological environment. Methods: The images and data were obtained from a contact mode and commercial Si3N4 probed tip by using atomic force microscope (AFM). Conclusions: Using AFM to investigate biomacromolecule can make us deeply understand the structure of IgG, which will instruct us to detect the membrane receptor protein as a labelling agent.