The seeds of wild Idesia polycarpa obtained from Liupanshui City, Guizhou Province were used as experimental materials in this study, where the seeds were treated with different irradiation doses of ⁶⁰Co-γ ray. The effect of ⁶⁰Co-γ ray irradiation on the seedling rate, ground diameter, seedling height, leaf length, leaf width, leaf area, leaf circumference, secondary root length, secondary root diameter, and chlorophyll content of 1-year-old I. polycarpa were investigated. The results showed that compared with the control, ⁶⁰Co-γ irradiation treatment significantly increased the seedling rate of I. polycarpa and had significant effects on the growth of I. polycarpaseedlings (p<0.05). Under an irradiation dose of 120 Gy, the ground diameter and seedling height of the I. polycarpa seedlings were the largest, i.e., 36% and 68% higher than those of the control, respectively. With the increase in irradiation dose, the length of secondary roots, the thickness of secondary roots, and the number of tertiary roots increased significantly, reaching maximum values at 120 Gy. The chlorophyll content of I. polycarpa leaves first increased, then decreased, and then increased again. Mutant plants with high growth, stem bending, deformity, multi-branching, and dwarfing were produced via ⁶⁰Co-γ ray irradiation. The irradiation dose of ⁶⁰Co-γ ray was significantly correlated with most of the growth traits (p<0.05). The results above show that ⁶⁰Co-γ ray irradiation can improve the seedling emergence rate of I. polycarpa, promote the growth and root development of I. polycarpa, and yield a few different types of mutant plants, thus providing an important theoretical basis for the creation of new germplasms of I. polycarpa.