<p>To better investigate potential risk contagion in guarantee networks, we propose risk contagion and threshold models based on a supply chain consisting of capital-constrained firms and suppliers. The results show that the optimal debt payment and asset liquidation strategy can help firms improve their payment ability and minimize liquidation losses suppliers, ultimately leading to agreement on debt repayment among all parties in the supply chain. When a guarantee network exists in the supply chain system, the optimal general guarantee under the threshold contagion model minimizes risk spillover and does not require the guarantee ratio to be necessarily full. In addition, we find that when product order quantity increases or actual market sales quantity increases, firms’ expected revenue increases or economic losses decrease, thereby reducing the likelihood of penalty guarantee agreements and decreasing supplier and firm defaults and asset losses. Similarly, during the network formation process, when the guarantee fee rate rises, some firms may refuse to accept suppliers’ guarantees, making it impossible to establish guarantee relationships. Finally, under certain conditions, we suggest that regulators recommend general guarantee schemes to supply chain systems to reduce systemic risk.</p>