The microstructures and micro-defects in laser-recrystallization SOI （Silicon on Insulator） with reflecting-stripe structure have been studied using plane-view and cross-section electron microscopy. The experimental results indicate that the silicon film laser-recrystallized under the normal processing conditions can be divided into three distinct regions:monocrystal with [100] orientation in the middle of the melted zone

recrystallized large grains in the both sides of the monocrystal and polycrystal zone in the most outside side. When the processing is not proper

subgrain boundaries and large angle grain boundaries appear in "monocrystal region"; 180°microtwins arrayed regularly on both sides of the "monocrystal region" can be observed sometimes

and their twin planes are {111}. The orientations of the large grains are not regular. The polycrystal region consists of columnar grains with obvious texture. The cause of the defect formation is also discussed in this paper.