Abstract:Cathay hickory has more flowers, but less fruit, a lower fruit set percentage, which is one of the problems in its production. Its female flowers have a long flowering period and a habit of waiting for pollination. A 4-year trialshows that its fruit set percentage might be increased by 40% or so by assistant pollination. With exroot nutrition, applying 0.3%B+0.3% urea and 0.3%B+0.3% P or K the fruit set percentage could be increased on an average by32.4% and 31.3% respectively compared with the contral. Chemicals and exogenous hormones which have remarkable and stable effect on fruit setpercentage during the flowering period are 0.02% CuSO4 sprayed and 0.1-0.2% CuSO4 brushed on the trunk, which increase the fruit set percentage by30.1-126.8% and 24.2-26.2% respectively compared with the control. Spraying 0.01-1.00ppm TRIA during the flowering and young fruit period andbrushing 10ppm TRIA on the trunk, the fruit set percentage could be increased by 8.7-16. 3% and 50% or so respectively. Brushin 5ppm NAA on the trunk and spraying 40ppm IAA during the flowering period could increase the fruit set percentage by 34. 8% and 42.2% respectively. The fruit sets of suchtrees which are in poor physiological status, could be increased by some agri-cultural measures, such as rootbreaking, barkcutting, girdling and stickingthe bark reversely, and so on, in an average of 29.4%, 32.1% and 36.7%respectively.