Abstract: In order to explore the effects of ⁶⁰Co-γ ray irradiation on the pollen germination of different macadamia cultivars, the fresh pollen of macadamia cultivar‘HAES900’and‘HAES951’were irradiated by ⁶⁰Co-γ ray at different dose with the dose rate of 10 Gy/h, the pollen viability and morphology were observed. The results indicated that the in vitro pollen germination rate of‘HAES900’increased with dose increasing after low dose irradiation and the pollen germination rate of‘HAES951’increased firstly and then decreased. After irradiation at high dose, the in vitro pollen germination rate of‘HAES900’increased firstly and then significantly decreased, and‘HAES951’decreased significantly. The variation of pollen tube length in the same treatment was larger after irradiation of ⁶⁰Co-γ ray at high dose; some pollen tubes appeared distorted or intumescent at the top. The lethal dose of both‘HAES900’and‘HAES951’were 600 Gy, but the LD50 of‘HAES900’and‘HAES951’was 480 Gy and 360 Gy respectively. The study found that irradiation of ⁶⁰Co-γ ray at low dose could promote the macadamia pollen germination in vitro and at high dose could inhibit the pollen germination; the cultivar‘HAES951’was more sensitive to ⁶⁰Co-γ ray irradiation.