Mechanical harvesting can cause damage to the flower buds of Camellia oleifera, which affects the fruit yield of the following year. In order to investigate the influence of mechanical harvesting of fruits on the yield of C. oleifera in the second year and ease the nutritional competition by rational loading, this study designed flower thinning treatments at the intensities of 0%, 30%, 50%, and 70% for the 10-year-old plants of the C. oleifera cultivar 'Cenruan 3' and then determined the fruit yield and oil quality. The results showed that the fruit volume, fruit weight, ratio of seeds to fresh fruits, ratio of kernels to seeds, and kernel oil content increased with the increase in flower thinning intensity. The yield per plant and oil yield per plant in the 50% thinning treatment of C. oleifera in the second year increased significantly by 44.51% and 43.25%, respectively, while they had no significant difference between 30% and 70% treatments and the control. The 50% and 70% treatments showed increased content of oleic acid and palmitoleic acid but decreased content of palmitic acid, stearic acid, linoleic acid, and linolenic acid. The unsaturated fatty acid content and oleic acid content were in the descending order of 70% treatment > 50% treatment>30% treatment. Through the flower thinning treatment, the unsaturated fatty acid content reached 88.88%-89.01% and the oleic acid content reached 78.2%-79.1%. In summary, 50% of flower thinning can significantly improve the fruit yield and oil quality compared with the control. The results provide a reference for artificial flower (bud) thinning and mechanical harvesting of C. oleifera fruits.