Purpose: To provide a feasible way to examine nucleoli changes in a real-time manner after exposure to ionizing radiation (IR).Materials and methods: We constructed NPM gene into pEGFP-N2 vector and subsequently transfected it into human melanoma 92-1 cells.Results: Successfully we established a cell line stably expressing NPM-pEGFP fusion protein by selecting with G418, which might be a powerful tool for studies on the nucleoli in responding to exogenous stresses.Conclusions: Our data shows that both 12C6+ ions and X-ray irradiation could cause nucleoli to change their morphological structure, size etc.This result indicates that nucleoli changes may have some relationship with cells response to radiation.So, the further study ofnucleoli structure and constitutive proteins changes could show us a new way to study molecular mechanism of cell biological effects of radiation.