Abstract: Nuclear medical molecular imaging is developing toward a multimodality and multitracer future. Abundant complementary data generated from different tracers in different modalities are successfully serving the biological research and clinical treatment. Among the others, PET-MRI has the greatest potential and will be a research of interest in the near future. This article focused on the evolution history of nuclear medicine from single modality to multimodality, single tracer to multitracer. It also gave a brief summary to the identifications, differences, pros and consofmultimodality, multitracer, multiparametric molecular imaging. Issues, problems and challenges concerned with her development and recognition are also discussed.