The invention relates to a cross-scale full-automatic occluded foreign substance quick analyzing instrument and a method based on a microphotographing matrix. The analyzing instrument comprises a microphotographing matrix system, a high precision three-dimensional numerically controlled worktable, a computing working group and a control and data processing system. A to-be-tested sample is a largedimension metal member, the microphotographing matrix system can be movably fixed to the Z axis of the high precision three-dimensional numerically controlled worktable up and down, and the computingworking group controls the displacement of the high precision three-dimensional numerically controlled worktable according to the control and data processing system to move the position of the to-be-tested sample step by step, so that the microphotographing matrix system traverses to-be-tested surfaces of all to-be-tested samples to achieve full-scale microphotograph of the to-be-tested samples soas to carry out occluded foreign substance searching, area computing, positioning, shape graded amplification and statistic distribution analysis. By combining the microphotographing matrix with highspeed operation, the scanning dimension of the sample is large, the precision is high and the speed is high. The analyzing efficiency of the large scale sample occluded foreign substances is improvedobviously.