<p>Amid the growing prominence of the platform economy, the strategic choices of functionally differentiated platforms in the secondhand market have become a critical issue. This study explores the partnership between a primary platform (E1) and a secondhand recycling or sales platform (E2), analyzing how different modes impact their decision-making and profitability. To explore whether E1 participates in E2’s recycling or secondhand sales mode, we first study the case of non-participation mode as a benchmark. The results shows that when the refurbishment cost is high, E1 gains the highest profit by engaging in secondhand sale, while E2 benefits more from engaging in recycling. Under certain conditions, a non-participation scenario may exert an environmental impact, leading to positive effects on consumer surplus and social welfare. In contrast, both engagement in recycling and engagement in secondhand sales can lead to mutually beneficial outcomes, particularly under all-resale and no-resale strategies. In our extended analysis, we explore the impact of platform power on the profit of each member and find that it generally benefits E2. In addition, when E1 pursues a dual objective of both profitability and consumer surplus, consumer surplus always benefits, and E1 benefits from consistent profitability under certain conditions. Finally, when there is uncertainty in the quantity of secondhand products, we find that as demand uncertainty increases, the expected profit of both platforms follows an upward (downward) trend in all-resale and no-resale (partial-resale) strategies.</p>