1． College of Geo- Exploration Science and Technology， Jilin University， Changchun 130026， China; 2． Baixian Company，Northeast Electric Power Design Institute Co．，Ltd． of China Power Engineering Consulting Group， Changchun 130021，China

In the multi- wave and multi- component seismic exploration，shear- wave will be split into fast wave and slow wave， when it propagates in anisotropic media． Then the authors can predict polarization direction and density of crack and detect the development status of cracks underground according to shear- wave splitting phe- nomenon． The technology plays an important role and shows great potential in crack reservoir detection． In this study，the improved particle swarm optimization algorithm based on shrinkage factor is combined with the Pear- son correlation coefficient method to obtain the fracture azimuth angle and density． The experimental results show that the modified method can improve the convergence rate，accuracy，anti- noise performance and compu- tational efficiency．