Abstract:Distant hybridization was carried out by using hexaploid triticale,Heizlha 266,as female parent and 2 varieties of spring wheat ,Longfumai 3 and Longfumai 5,as male parent which were irradiated by slow irradiation of living bodies with 60Co gaxnula rays froln 600 to 2400rad before distant hybridization, Through the observation of pollen mother cells of first gen-eration of distant hybrilization(M1),it was found that the amount of bivalents at meiosis metaphase was 13.65 on average,and was l4.55 on maximum, which were close to theoreti- cal value, but the corresponding amount of bivalents at the same stage produced by unirradi-ated polleu mother cells were l2.80 , which were lower than theorectical value. Chrolmosomepairing was improved by irradlation, Average setting ratio of M1 generation affected by irra- diation was 52.85 %, but the corresponding figure for F1 generation affected by unirradiationwas 6.49%, It is obvious that irradiation treatment increases setting rate of M1 hybrid gener- ation.The optimum doses for irradiating androgametes are 1600 and 2400 rad,respectively. However,there are signincant differences of irradiation sensibility between different vari- eties of wheat.