This research provides a method of Random Generation of Soil-rock Mixture(SRM) models depends on digital imaging technology and rock block database technology and analyzes the parameter influence to SRM backfilled slope stability with Finite element method(FEM).With processed rock shape diagrams, database of rock shape had been built and a method of random generation depend on this database had been provided. This method avoids the fiction of rock shape in general SRM random distribution and the difficulty of model data acquisition with digital imaging technology. The SRM backfilled slope models are generated with random generation method provided before. Couples of slope models had been simulated with ABAQUS CAE to study the stability of SRM backfill slope with changing factor like block content parameters. Result shows that the blocks can delay the growth of slip surface compared with uniform soil slope. In addition, with the increase of block content, the stability of slope increased in a non-uniform trend. Large size blocks and small size blocks aggregation at the low part of slip surface can increase the slope stability effectively by changing the shape of slip surface. With the increase of maximum block size, the slope stability decreases first and then increases.