A field experiment was conducted to systematically compare the effects of trifoliate orange (Poncirus trifoliata) and sour pummelo (Citrus grandis) rootstocks on tree growth and fruit quality in six-year-old 'Haruka' tangelo. The results indicate that the tree vigor of 'Haruka' grafted onto sour pomelo rootstock was significantly stronger than that grafted onto trifoliate orange rootstock. The tree height (135.2 cm–159.4 cm), east-west canopy spread (188.2 cm–198.1 cm), and canopy volume (3.99 m3–4.24 m3) increased by 15.01%–20.90%, 17.07%–21.58%, and 46.21%–48.88%, respectively, with better compatibility. There were no significant differences between the two rootstocks in terms of the number of spring shoots, leaf size, or flower bud formation. However, the length and diameter of spring shoots on sour pomelo rootstock were significantly greater than those on trifoliate orange rootstock by approximately 19.64% and 13.30%, respectively, indicating more robust development. The fruit set rate and yield per plant of sour pomelo rootstock were also significantly higher, with an increase of 4.8 kg per plant. Meanwhile, the leaves of 'Haruka' on sour pomelo rootstock showed deficiencies in N, K, Mg, and Cu, and the contents of N, P, Mg, and Mn were significantly lower than those on trifoliate orange rootstock. In contrast, the leaves of 'Haruka' on trifoliate orange rootstock exhibited Zn deficiency and insufficient K and Cu contents. In terms of fruit quality, trifoliate orange rootstock performed better, with soluble solid content in mature fruits ranging from 12.5 Brix° to 12.9 Brix°, approximately 1 Brix° higher than that of sour pomelo rootstock, mainly due to a significant increase in sucrose content. Additionally, the leaf chlorophyll content (SPAD value) and net photosynthetic rate of trifoliate orange rootstock were significantly higher than those of sour pomelo rootstock, indicating higher photosynthetic efficiency. In summary, 'Haruka' on sour pomelo rootstock is suitable for high-yield cultivation, while 'Haruka' on trifoliate orange rootstock has advantages in terms of intrinsic fruit quality.