In order to study evolution trend of key risks in urban regional work safety and establish an effective risk control mechanism, according to actual survey results in a prefecture-level city in Jiangsu Province, main risk factors in three key industries, namely transportation, construction and commercial places, were deeply analyzed in view of their field characteristics. Then, a system model of key risks in urban work safety was constructed by using SD theory and method, and risk value was dynamically simulated by adopting Vensim software. Finally, countermeasures to improve urban intrinsic safety were put forward from perspectives of actual risks of the three key industries based on survey data and simulation results. The results show that the evolution trend of key risks in urban work safety is roughly as slow decrease → extremely rapid decrease → gradual flattening out. Moreover, risk influencing factors, total risk, number of risk elimination, rate of risk elimination, and turning point of risk elimination of the three key industries are different due to different industries.