Demands for ultra high precision non destructive detection of micro bulk defects in materials have manifested as microelectronics and micro electro mechanical system (MEMS) rapidly develops. But at the same time, although many high precision non destructive defects detection methods exist now, they still can′t meet the requirements at all. In this paper, after having established a mathematical modeling of detecting micro bulk defects by Rayleigh & Mie theory, a novel way, which collects scattered light in the direction vertical to the incident laser and can detect micro-bulk defects in materials, is proposed. In order to prove the rightness of the modeling and technique, simulation experiments on microsize diamond particles are implemented and the scattered graph collected in the direction vertical to the incident light is processed. Satisfactory result is achieved which demonstrates that the scattering modeling and technique are correct and that the LST non-destructive detection of micro-bulk defects is feasible.