The main purpose of China's reclamation in the South China Sea is

Territorial sovereignty and national security, resource development and utilization, maritime traffic and shipping guarantee, etc.

1. Territorial sovereignty and national security: The South China Sea is the location of China's important territorial and maritime rights and interests. Reclaiming land can strengthen China's actual control and sovereignty declaration in the South China Sea. By building military facilities and infrastructure, we will strengthen the military presence and defense capabilities in the South China Sea and safeguard national security and territorial integrity.

2. Exploitation and utilization of resources: The South China Sea is rich in marine resources, including oil, natural gas and fishery resources. Island reclamation can provide more land area for China, which is beneficial to the development and utilization of marine resources and meets the needs of domestic energy demand and economic development.

3. Maritime traffic and shipping guarantee: The South China Sea is an important international shipping channel. Reclaiming land from the sea can build ports, docks, waterways and other infrastructure, provide better maritime traffic and shipping support capabilities, and promote economic and trade cooperation.