本文提出矩形薄板振动主振方向的概念。根据振形正交性的思想 ,在主振方向上矩形板振动波形是唯一的 ,由此建立了符合矩形悬臂板边界条件所激发出的振动曲线形态的振形函数表达式 ,并推导出矩形板的频率方程及相应的振形曲线。计算表明 ,这种方法符合板实际振动的规律性 In this paper, the concept of the vibration direction of the rectangular thin plate is proposed. According to the idea of ​​shape orthogonality, the vibration waveform of the rectangular plate in the direction of the main vibration is unique, so the vibration shape function expression of the vibration curve which is in accordance with the boundary condition of the rectangular cantilever plate is established and the rectangle The frequency equation of the plate and the corresponding vibration curve. Calculations show that this method meets the regularity of the actual vibration of the slab