Abstract: 【Objective】Exploring effects of heavy ion irradiation on grain protein and processing quality of wheat,in order to provide new ideas and theoretical basis for high-quality wheat breeding.【Method】Medium-strong gluten wheat Lianmai 12 and medium gluten wheat Huaimai 20,which were suitable for planting in Huaibei region of Jiangsu,were used as test materials. Four irradiation dose treatments of 0(CK),30,60 and 90 Gy were set to analyze changes of grain protein content,milling quality,flour properties and extension properties of wheat.【Result】Heavy ion irradiation negatively influenced grain processing quality of wheat to some extent. As irradiation dose increased,content of total grain protein and its components of Lianmai 12 and Huaimai 20 decreased significantly,with content of total protein and gluten decreased obviously. At the same time,wet gluten content,volume weight,sedimentation value,hardness,flour parameters and extension parameters of wheat decreased. Under 90 Gy irradiation dose,wheat processing quality indexes was the lowest value and total protein content,wet gluten content,stability time and extension area of Lianmai 12 and Huaimai 20 were 13.49%,31.1%,6.8 min,61 cm² and 13.19%,28.1%,3.9 min,25 cm² respectively. There were some differences regarding effects of heavy ion irradiation on grain quality between 2 wheat varieties existed. Under 30 Gy irradiation dose,decreasing range of grain toatl protein content of Lianmai 12 was 2.14%,which was higher than that of Huaimai 20(1.43%),while decreasing range of milling quality of Lianmai 12 was lower than that of Huaimai 20;as irradiation dose reached 60 Gy,total protein and milling quality of Lianmai 12 decreased more obviously compared to Huaimai 20. Under irradiation dose of 30-90 Gy,decrease range of farinograph parameter and extension parameter of Huaimai 20 dough was higher than that of Lianmai 12. Under 90 Gy irradiation dose,water absorption rate,stability time,farinograph quality index,maximum extension resistance,extension area and extensibility of Huaimai 20 decreased by 5.18%,30.36%,44.29%,35.51%,45.65%,26.53%,respectively.【Conclusion】Heavy ion irradiation negatively influenced grain quality of wheat mutation population to some extent. Such negative effect grows greater as irradiation dose increases. Low dose of heavy ion irradiation greatly influences milling quality of Huaimai 20 while medium and high dose of heavy ion irradiation greatly influences milling quality of Lianmai 12. In terms of rheological properties,heavy ion sensitivity of Huaimai 20 dough is relatively higher.