Choosing a model animal is a critical decision in basic and applied biology research. Model animals usually include mice, rats, fruit flies, nematodes, zebrafish, etc. Factors such as biological characteristics, genomic similarity, experimental convenience, and cost need to be considered when selecting. Mice are widely used in genetics and immunology research, rats are used in physiology and drug testing, fruit flies and nematodes are widely used in developmental biology and neuroscience, and zebrafish are mainly used in biological imaging and developmental research. Proper selection of model animals can improve experimental reproducibility and result applicability.