Objective To conduct a quantitative risk assessment for Staphylococcus aureus in ready-to-eat salads, and seek effective preventive measures according to the risk assessment result. Methods Combining quantitative data of Staphylococcus aureus with residents’ consumption data of ready-to-eat salads, a quantitative risk assessment was performed according to the codex guidelines with four steps:hazard identification, hazard characterization, exposure assessment and risk characterization. A Monte Carlo simulation method was employed to analyze the health risk of Staphylococcus aureus by consuming ready-to-eat salads. Results The contamination rate of Staphylococcus aureus in ready-to-eat salads was 3.39% (21/620) and the average concentration was 229 CFU/g. The average intake was 56.27 times per year. The estimated probability of infectious illness caused by Staphylococcus aureus in ready-to-eat salads in Shanghai was 0.04%. That indicated the number of illness might reach 518.1 thousand cases every year. Conclusion There was certain risk of Staphylococcus aureus poisoning by consuming ready-to-eat salads for Shanghai residents. Decreasing initial contamination level and controlling the storage time and temperature were the critical approaches to reduce its risk.