介绍了利用有限差分方法进行地震走时资料速度反演的基本原理与方法,并对理论模型进行了正演和反演。然后对唐山滦县的Pg 波三维资料和菏泽—林县—长治的二维Pg 资料分别进行了三维和二维反演,反演结果与浅层地质资料较好吻合,由于反演是采用不用矩阵运算的反投影方法,可以实现稠密采样,这为我们提供了一种较好的得到高精度浅层速度的办法,为深部结果的反演提供了可靠的浅层速度资料。 This paper introduces the basic principle and method of using the finite difference method to retrieve the seismic data traveltime, and forwards and inverses the theoretical model. Then three-dimensional and two-dimensional inversion of Pg wave data in Tangshan Luanxian and two-dimensional Pg data of Heze-Linxian-Changzhi were carried out respectively. The inversion results are in good agreement with shallow geological data, The backprojection method of matrix operation can realize dense sampling, which provides us a better method of obtaining high-precision shallow velocity and provides reliable shallow velocity data for the inversion of deep results.