According to the airport security regulations, as long as the battery capacity does not exceed 100wh, small fans powered by rechargeable or dry batteries can be used. Usb handheld fan does not have such a large capacity, so it is ok to take it with you on the plane and put it in your carry-on bag.
Articles prohibited from being carried and checked by aircraft:
Carrying guns (including all kinds of simulated toy guns, miniature launchers and all kinds of offensive weapons), ammunition, ordnance, police equipment, explosives, inflammable and explosive substances, highly toxic substances, radioactive substances, corrosive substances, dangerous solutions and other prohibited items on the plane or checking luggage and articles. Anyone who carries or entrains the above items shall be immediately handed over to the public security organ for handling.
Relevant regulations:
The Civil Aviation Safety Inspection Rules stipulate that:
Article 41? For articles that passengers are forbidden to carry with them but can be checked, the civil aviation security agency shall inform passengers that they can be checked as luggage, handled by themselves or handled temporarily.
The civil transport airport management institution shall provide temporary storage services for articles that passengers need to temporarily store. The storage period of temporary storage items shall not exceed 30 days.
Civil transport airport management agencies shall provide conditions for keeping or disposing of articles temporarily stored, abandoned or left behind by passengers during civil aviation safety inspection.
Article 49? For oversized and overweight air cargo that cannot pass the air cargo security inspection equipment, safety measures should be taken to park it in isolation for at least 24 hours before loading it into the aircraft, and explosives should be detected and checked.
Article 50? Postal enterprises shall submit documents or electronic data such as parcel waybill, detailed mail name and quantity list audited by public air transport enterprises or their ground service agents before carrying out security inspection on air mail.
Article 51? Airmail shall pass the inspection of civil aviation cargo security equipment in accordance with the requirements of airmail security inspection. If there is no doubt about the inspection, the civil aviation security inspection agency shall affix an inspection mark to release it.
Civil aviation administration of China-security inspection