On January 19，2019，a case of African swine fever（ASF）was confirmed in Banqiao Village，Wangyuan Town，Yongning County，Yinchuan City of Ningxia. In order to find out the causes，analyze any possible risks and to put forward effective suggestions to prevent and control the disease in time，an investigation was carried out by combination of emergency epidemiological investigation and laboratory testing. The time，space and inter-population distribution of the outbreak were described，a hypothesis was established and verified according to case-finding，field investigation and tracing，and then all possible routes of disease spreading were closed. It was investigated that the outbreak might be caused by feeding pigs with kitchen waste or vehicles/personnel carrying the virus entering into the farm in late December 2018，but the risk of virus spreading was relatively low. It was suggested that the screening and monitoring for the epidemic should be strengthened，supervision over transportation of live pigs and pig products as well as the use of kitchen waste should be enhanced and improved，the responsibilities of producers and operators should be well in place，so as to ensure ASF could be effectively prevented and controlled. As it was verified in this paper that ASF could be prevented and controlled through banning feeding with kitchen waste and strengthening disinfection and control over movement of vehicles and personnel.