Legal analysis: illegal, refusing consumers to bring their own drinks violates consumers' right to choose independently.

Legal basis: People's Republic of China (PRC) Consumer Protection Law.

Article 9 Consumers have the right to choose their own commodities or services.

Article 10 Consumers have the right to fair trade. When purchasing goods or receiving services, consumers have the right to obtain fair trading conditions such as quality assurance, reasonable price and correct measurement, and have the right to refuse the compulsory trading behavior of operators.

Twenty-fourth operators shall not make unfair and unreasonable provisions to consumers in the form of standard contracts, notices, statements, store notices, etc. , or reduce or exempt its civil liability for harming the legitimate rights and interests of consumers.