The impacts of COVID-19 on supply chain system have been dramatic, reflecting that most supply chains both in China and across the world were insufficiently resilient when facing with multiple risks and changes in supply and demand. The pandemic itself and the strategies that organisations and firms have responded to it, provide opportunities to have an in-depth understanding of the supply chain management in China's context. Green supply chain management (GSCM) practices, integrating internal certification and external recovery strategies within the management process, may be the key to resolving the above problems. In this research, we first explored the strategies of marketing (e.g. price discount) in a special period, Double Eleven Shopping Festival which lasts from 1st November to 11th November. We selected JD as the online shopping platform for the reason that JD is one of the largest e-commerce platforms in China. Then, we tested the dependently and interdependently moderate effect of external GSCM practices (i.e. green recovery) and internal GSCM practices (e.g., green certification) and on the value of price promotion based on synergy theory. Using hierarchical regression, our results show that there is a positive relationship between discounts and sale changes. Both internal and external practices have a positive moderate effect on the value of marketing strategy. Furthermore, the internal and external GSCM practices are complementary in moderating the link between marketing strategy and firms' sales performance. There is an obvious boost of both demand and supply under the synergetic application of price discount strategies and GSCM practices even under the COVID-19 pandemic. These findings provide implications for Chinese organisations in how to respond to the disruptive challenges brought by COVID-19 by shifting their focus on GSCM practices.