Abstract: The Quadratic/Linear Traveltime Interpolation (QLTI) ray tracing method is adopted to get the P-wave traveltime of crosswell seismic tomography in this paper. The Niche Genetic Algorithm is applied to the inversion of vertical velocity and anisotropic parameters. The sharing function is used in the population evolutionary process to select the individuals, which can well maintain the individual variety and keep off trapping in local minima to some extent. The numerical simulation shows that the precise anisotropic parameters and high stabilization can be obtained by using this inversion method. The multi-scale inversion can improve the precision of inverted results even in short offset.