As an important force to accelerate the development of new quality productive forces, "specialized, refined, differential and innovative"(SRDI) enterprises have significant implications for China's realization of high-level scientific and technological self-reliance and self-sufficiency through their diversified technology strategies. Based on the resource-based view and diversification theory, an empirical analysis was conducted on the non-balanced panel data of 703 listed SRDI enterprises in China from 2018 to 2022 to explore the relationship between technological diversification and breakthrough innovation performance, and analyze the moderating effect of industry competition on the main effect. The impact of both related and unrelated technological diversification on the breakthrough innovation performance of SRDI enterprises is observed to be positive, with related technological diversification demonstrating a more pronounced enhancement effect. Industry competition interaction is found to weaken the positive influence of related technological diversification on breakthrough innovation performance, while no significant moderating effect is detected in the case of unrelated technological diversification. Conversely, higher industry competition intensity is revealed to strengthen the positive relationship between unrelated technological diversification and breakthrough innovation performance, whereas no significant moderating role is observed for related technological diversification. These findings contribute to the existing research on factors influencing breakthrough innovation in SRDI enterprises, offering strategic references for selecting technological diversification approaches under varying competitive environments under the new development pattern.