Is it illegal for normal people to wear security clothes?

Legal analysis: not illegal. Security clothing is the uniform clothing of the security service industry. Only military and police uniforms can't be worn casually. Others are professional clothes, similar to school uniforms. Personal wear is not illegal. But security guards should wear security clothes when they are on duty, and they should not wear security clothes when they are not on duty. If they wear them, it's against company discipline.

Legal basis: Regulations on the Administration of Security Services

Article 16 China citizens who have reached the age of 18, are in good health, have good conduct and have a junior high school education or above may apply for a security guard certificate and engage in security services. If the applicant has passed the examination by the public security organ of the municipal people's government with districts and retained human biological information such as fingerprints, he shall be issued with a security guard certificate. Specific measures for extracting and retaining security guards' fingerprints and other human biological information shall be formulated by the public security department of the State Council.

Twenty-seventh security guards should wear the clothing of security guards and the uniform national security service marks. Security guards' clothing and security service signs should be obviously different from the standard clothing and logo clothing of China People's Liberation Army, People's Armed Police, People's Police, Industrial and Commercial Taxation and other administrative law enforcement organs, as well as people's courts and people's procuratorates. Security guards' clothing is recommended by the National Security Service Industry Association and selected by the security service business unit within the recommended style range. The style of security service marks shall be determined by the National Security Service Industry Association.