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Hybrid incompatibility and F₁ hybrid dysgenesis in the interspecific hybridization between pumpkin (<i>Cucurbita moschata</i> Duch.) and winter squash (<i>Cucurbita maxima</i> Duch.) have been previously noted. For this reason, it is difficult to obtain F₂ generations due to F₁ sterility. However, back-crossing and add-crossing can be utilized to overcome these incompatibility barriers in interspecific hybridization. To date, few studies have focused on parental selection, the back-crossing process, and offspring characteristics related to interspecific hybridization. Hence, we explored the F₁ seed acquisition rate, plant characteristics, and F₂ generation fertility after interspecific back-crossing and add-crossing hybridization of <i>C. moschata</i> and <i>C. maxima</i>. Moreover, as a female parent, X-1 (<i>C. moschata</i>) yielded F₁ seeds when crossed with winter squash (<i>C. maxima</i>) 10-04-3, 10-37, or 10-05-2. BC₁F₁ seeds and plants could be obtained with winter squash (<i>C. maxima</i>) as the recurrent parent. Some healthy F₂ seeds and plants were obtained from the interspecific hybrids, including ZJ-13, ZJ-8, and ZJ-11. Further fruit nutrition quality analysis showed that the starch, polysaccharide, cellulose, and dry material contents of ZJ-7 and ZJ-8 were significantly higher than those of the parent pumpkin and winter squash lines. The bioflavonoid content of ZJ-8 was lower than that of its parents, and its soluble protein was at the median value. Meanwhile, the bioflavonoid content of ZJ-1 was lower than that of its parents, but its soluble protein was significantly higher. These results suggest that back-crossing and multi-crossing can overcome the barriers to interspecific crossing of <i>C. moschata</i> × <i>C. maxima</i>. Some interspecific hybrid fruits had nutritional contents much higher than those of their parent lines. Additionally, X-1 (<i>C. maxima</i>) was found to act as a bridge species in interspecific hybridization. Collectively, in this study, the barriers to interspecific hybridization of <i>C. moschata</i> × <i>C. maxima</i> were addressed through crossing methods and choice of parents, and the obtained results are expected to provide novel support for interspecific hybrid breeding between <i>C. moschata</i> and <i>C. maxima</i>.