A new method for measuring the sound intensity level ( Sll,) using a rotating Rayleigh disk isproposed.The theoretieal analysis of the motion of the disk in a plane wave sound feld is presented ,and thedifferential equation of the disk's rotation is derived.The time-domain and frequeney-domain diagrams of thedisk's rotation angle and the equilibrium position of the disk under different Sll, sound fields are numericallyealeulated, Based on the frequeney domain diagram of the disk's rolation angle ,the Sll and rotation fiequeneyrelationship curve of difkerent parameters Rayleigh disk is obtained.The experimental results of different wirediameter Rayleigh disks are tested , and the experimental results are consistent with the theoretical caleulation,with a relative error of 0.0196-3.0396 between them ,especially in the high Sll, range ,showing higher precision.Compared with the traditional method of measuring the equilibrium position ofthe disk by using a complexoptical system , this method is more convenient and has higher precision.