With the popularity of casual puzzle games, their simple and easy to use gameplay and design that challenges the limits of players, as well as the needs of multiple platforms, are gradually becoming a widely pursued choice. This paper mainly discusses how to accurately simulate the core logic of Tetris game, including the fall, rotation, deformation, etc. How to design an intuitive game interface, including game areas, block previews and score displays; How to effectively handle the player's keyboard keys and mouse clicks to control the game progress; And how to design game difficulty adjustment mechanics to meet the needs of different players. Therefore, the first definition of the block class, including the shape, color, position and other properties of the block, as well as rotation, deformation and other methods, to achieve the control of the fall of the block, detection of collision and the end of the game conditions. Then use the Java Swing library to create a game interface, design the layout of the game panel, and then add a keyboard monitor for the game panel, used to monitor the player's keyboard key events, to achieve the game start, pause, continue button functions. Finally, the difficulty level is designed to change the difficulty of the game by adjusting the falling speed of the block and adding special blocks.