For many years, China’s steel exports have been winning with low prices. As the upstream iron ore price rises, the profit margin is compressed while many problems are exposed. The author has constructed a SWOT-AHP model for the cross-border financial transaction link of steel foreign trade and analyze the main factors affecting the financial transactions of steel foreign trade by calculating the weights within the SWOT group and among the factors and ranking them. The results show that transaction credit risk, long and inefficient settlement cycle, changes in steel tax rebate policy, high cross-border transaction costs, and rising upstream raw material prices are the main factors for the development of China’s foreign trade in steel. Relying on blockchain technology, it will be improved and its application path in cross-border financial transactions will be explored to achieve the purpose of avoiding credit risks on both sides of transactions and reducing time and costs of foreign trade transactions. At the same time, it breaks the monopoly of cross-border transactions of the SWIFT system and optimizes the financial transaction mode of foreign trade of steel, and with the background of the E-CNY R&D pilot, we construct the application path of E-CNY cross-border payment under blockchain technology and provide some theoretical support for the promotion of E-CNY internationalization.

Carbon peaking and carbon neutrality will be important policies to constrain China's economic and social development in the future. Based on the theory of computable general equilibrium, CGE model of carbon emission was constructed in this paper to simulate the influence of different scenarios of carbon emission reduction on economic and social development. The major contribution is to subdivide the energy sector according to primary energy and secondary energy, and construct the macro SAM table and micro SAM table of 21 energy sectors in 2017 to quantitatively simulate the impact of carbon emission reduction policies on China's economy and society, and put forward some policy suggestions based on this.