Abstract: In view of the easy defects in the casting process of flywheel, the section size of the flywheel and neck was determined by the basic theory and method of casting, and the casting process scheme of QT 500-7 flywheel was designed.Using the numerical simulation method and AnyCasting as the simulation platform, the temperature field characteristics during the flywheel filling process, analysis of solidification characteristics of filling process, analysis of the flywheel shrinkage release position and analysis of the flywheel probability defect characteristics were carried out. The simulation conclusion shows that the temperature at the position of riser and sprue is highest. Meanwhile, the isolated region of liquid metal in the flywheel during solidification is pointed out, and the possible shrinkage and loosening position of the flywheel is effectively predicted. The research results provide useful help for reducing the defective rate of flywheel and improving the manufacturing quality of flywheel, and also lay a foundation for the subsequent improvement of flywheel casting process.