Laser cooling of molecule is one of the most important progresses on the generation of cold molecules in experiments. To find a suitable candidate for laser cooling experiment, the molecular structure parameters and spectral data must be understood. These parameters are important basis of choosing molecules. The detailed calculations of vibronic structure and rotational hyperfine structure of the molecular X and A states are carried out. Considering the parameters of nuclear spins, excited lifetime, dark state,transition levels, and so on, a new suitable molecule (magnesium fluoride) for laser cooling is proposed, and the appropriate transition is used to form the quasi- closed energy level system for laser cooling. These parameters provide theory basis for the experimental measurement of spectral data, and lay a foundation for further laser cooling experiments.