Abstract: The aims were to study biological effect of the different neutron absorbed dosages on M1 generation of pea, and provide important cues for radiation biology and neutron mutation breeding. The dry seeds of Pisum sativum L. var MZ-1 were irradiated by ²⁵²Cf fission neutrons, and then biological effects of morphologic and physiologic of M1 generation were studied during the growth of pea. The result showed that, the neutron radiation (0.24-4.33 Gy) had promoting effect on germination and radicle growth of M1 generation of peas, low absorbed dose neutron irradiation (0.38 Gy) could promote the germination and radicle growth significantly. The higher neutron absorbed dose (1.66, 4.33 Gy) had inhibition on the plant height of M1 generation of peas. However, the plant height of M1 generation of peas was promoted by radiation of lower neutron absorbed dose (0.24, 0.38, 0.84 Gy). In addition, the morphologic variation on the M1 generation of pea was not shown by Micro dose of Neutron radiation, 0.84-4.33 Gy neutron absorbed dose could cause mutations in the branching of M1 generation of pea. These results indicated that biological effects of radiation were found on M1 generation of peas after low absorbed dose of 0.24-4.33 Gy irradiated dry seeds of pea, and had obvious rules, could be used in radiation breeding.