Abstract: Based on a supply chain consisting of one supplier who sells complementary products on an e-tailer's online platform through reselling or agency selling format, four Stackelberg game models were formulated to study the supplier's and the e-tailer's optimal bundling strategies and selling formats. The impacts of the degree of complementarity between products and the commission rate on the channel members' equilibrium prices and profits were also analyzed. The results show that the profits of the supplier and the e-tailer decrease as the degree of complementarity between products increases when the products are sold independently. The agency bundling is more advantageous to the supplier, while the reselling bundling is more advantageous to the e-tailer. Moreover, only when the commission rate is large enough, the e-tailer tends to use the agency selling format.