Spatially resolved metabolomics methods based on mass spectrometry imaging(MSI) technology have become a powerful tool for biological histology,molecular pathological diagnosis of tumor,and new drug efficacy and toxicology research.In this study,air flow assisted desorption electrospray ionization(AFADESI) with positive/negative mode switched scan was developed for MS imaging.With no need to apply high voltage during the ionization process,this method could not only improve the operating safety of ambient ionization,but also efficiently desorb and ionize various endogenous metabolites from biological tissue slices,especially large area whole body animal tissue slices.Furthermore,it could obtain the spatial distribution characteristics of those metabolites including polyamines,amino acids,phospholipids(easy to ionize in positive ion mode),nucleosides and phosphatidylglycerol(easy to ionize in negative ion mode).Through the simultaneous MSI analysis in positive or negative ion mode,the data collection time and the number of sample slices were saved,and the coverage of metabolites was expanded,while more types of metabolites could be detected in single experiment.Therefore,this method has the advantages in the spatially resolved metabolomics research on various tissues and organs of whole body animals,and it is expected to deeply understand the molecular spatial distribution characteristics and molecular mechanisms related to physiology,pathology and pharmacology at the metabolic level.