摘要This paper gives a detailed description of a radiological accident of 192Ir source occurring on May 7,2014 in Nanjing,China(the 5-7 accident),encompassing a combination of accident overview,emergency response,investigation process and results,dose estimation,medical treatment,experience and lessons learnt.The inves-tigation showed that the accident was mainly caused by insufficient attention to the radiation safety,non-compliance with licensing conditions and employment of untrained temporary radiographer without equipped with alarm dosimeters.Additionally,no area radiation survey meter was used to verify whether the source would have retracted to radiography camera after every exposure.It therefore is the important means to strengthen the management of radioactive source safety and put the strict management measures in place,implement the re-quirements for personnel qualification management,strengthen regulatory inspection and actively poster safety culture,which are necessary to avoid accidents.This paper aims to provide experience and reference for the emergency response and countermeasure of radiological accidents involving industrial radioactive sources.