1. social contributions: one of the main sources of social security funds is the social insurance contributions of individuals and enterprises. Individuals pay according to a certain proportion of their wage income, and enterprises also need to pay to the social security fund according to a certain proportion of the total wages of employees. These payment funds are used for social security projects such as pension, medical care, unemployment and work injury.

2. Government allocation: As the main provider of social security, the government supports the operation of social security funds through budgetary allocation. The government uses part of the funds for social security through taxation or other financial means to ensure that the basic social security rights and interests are guaranteed.

3. Investment income: Social security funds can also obtain certain income through investment and operation. Fund management institutions can invest some funds in stocks, bonds, real estate and other assets to obtain investment returns. These investment income can supplement the reserve of social security fund and ensure the long-term sustainability of the fund.

The general trend of social insurance fund development;

1. Expand coverage: The development of social insurance funds is usually accompanied by the continuous expansion of coverage. At first, social insurance may only cover a few workers in a specific industry. Over time, the scope of protection has gradually expanded to a wider range of industries and groups, including migrant workers and freelancers.

2. Improve the level of security: With the improvement of the social insurance system, the level of security will continue to improve. This includes increasing pensions, medical insurance and unemployment benefits to meet people's needs in retirement, medical care and unemployment.

3. Enhance financial sustainability: The financial sustainability of social insurance funds is the core issue of its development. In order to ensure the long-term stable operation of the fund, it is necessary to formulate reasonable payment policies, optimize investment operation management, prevent the fund from relying too much on government financial allocation, and ensure the sustainability of the fund.