1. Funding from the government or institutions: Some public interest law firms or teams may receive funding from the government or relevant institutions to support their work.

2. Donation and sponsorship: Public welfare lawyers can accept donations and sponsorship from all walks of life and provide them with certain economic security.

3. Compensation or compensation after the lawsuit is won: If the public interest lawyer successfully wins the lawsuit for the client and obtains corresponding compensation or compensation, then the lawyer can get a certain percentage of compensation.

4. Providing consulting and legal services: In addition to providing free legal services to clients, public interest lawyers can also provide fee-based consulting and legal services to those in need, thus earning a certain income.