After semiconductor laser irradiation on dry seeds of peanut with 0.25w/cm2 X 300s, 480s, at 650nm ,the effects of ultrastructures of plumule cell and chromosomal aberration have been studied in the present paper. The results showed many aberration types, such as earlier separated mitosis metaphase, variability of number, sticky, chromosomal laggards and ioop and so on were found in treatment group. With H-600 transmission electron microscope, the effects of ultrastructures of plumule cell were observed. There were difference in the cell on membrane system, fatbody and nucleus, especially in proteinbody. In this experiment, the sprout of peanut seeds( irradiated by semiconductor laser 0.25w/cm2x300s, 480s, 650nm) and generation agro-character also have been researched.