The presently claimed invention applies to an immunoassay apparatus based on micro-lens imaging technique and related product. In a preferred embodiment, the immunoassay apparatus comprises a monochromatic light source module, an intelligent auto-scanning and imaging module, a temperature controlled transparent toughened glass platform, a central control module, and a touchscreen displaying module. By automatically performing scan in focus imaging on the micro-lenses immersing in antigen-antibody solution and analyzing the data of the image, the apparatus can monitor the refractive index change of a sample solution before and after antigen-antibody reaction, so as to determine the concentration of antigen or antibody in the solution without requiring any labeling, expensive enzymes, pre-immobilization/modification, and post-washing. It can detect ultra-micro amount of Ag/Ab (˜pg/mL) in very low sample volume solution (several μL) within 2 minutes. It is of high accuracy and reliability. Moreover, the apparatus is simple and compact, can be portable for on-site immunoassay.