In order to explore the pollution characteristics and health risks of metal elements in PM_2.5 of Nanjing City， the mass concentration of 10 metal elements in PM_2.5 of Nanjing City in 2022 was collected and analyzed by using an online polymetal analyzer， the source analysis of metal elements was carried out by using PMF model， the health hazard of 5 heavy metal elements was assessed by health risk assessment method. The results showed that the average annual mass concentration of the 10 metal elements was 941.3 ng/m³，accounting for 3.4% of the average annual mass concentration of PM_2.5， Fe， K and Zn accounted for 91.2%. The analysis results of the sources of metal elements showed that the pollutants mainly come from soil dust， coal burning， straw burning， fireworks discharge， motor vehicle exhaust emission and mechanical wear. The results of health risk assessment showed that the HQ（hazard quotient） of Mn， V， Ni and As were all less than 1， indicating that there was no carcinogenic risk. The ECR（carcinogenic risk） of Ni and Pb（lead） is less than 10^-6， the risk is controllable; The ECR of As is between 10 ^-6 and 10^-4， there is a certain carcinogenic risk.