To operate a mobile dining car legally, it is necessary to comply with the following legal requirements: 1. Registration and establishment of a legal entity: the mobile dining car operator must register and establish a legal entity in the local industrial and commercial department, such as an individual industrial and commercial household or a limited liability company, in order to obtain a legal identity and relevant license. 2. Obtain necessary licenses: Operators need to apply for relevant food business licenses to ensure that food safety and hygiene meet the standards. At the same time, it is necessary to apply for a mobile vendor permit or a street vendor permit to legally set up a stall in a designated place. 3. Abide by environmental regulations: When choosing parking places, mobile dining cars should abide by relevant regulations to avoid blocking traffic or interfering with the normal life of surrounding residents. In addition, for specific areas, such as parks or business centers, it may be necessary to obtain special permission or comply with specific regulations. 4. Pay taxes and fees: Mobile dining car operators need to pay relevant taxes and fees according to legal requirements, including income tax and value-added tax. At the same time, it is also necessary to comply with the relevant tax declaration and tax return regulations to ensure that the business is legally taxed.