The invention discloses a respiratory infectious disease risk assessment system and method. The system comprises a model building module used for building a calculation model, an infection source feature analysis module used for simulating the process of breathing droplets out and the aerodynamics features of the process, an infectious substance diffusion and transportation analyzing module used for outputting the infectious substance diffusion and transportation analyzing result, a quantitative calculation module used for obtaining the susceptible population exposure level through a dosage-response model, and an infectious disease risk assessment module used for assessing the risk distribution in a space and outputting the risk distribution. By means of the assessment system, the requirements for accurately predicting the personnel infection level in the infectious disease transmission risk assessment can be met, the assessment system and method can be used for designing protection schemes and contingency plans of the respiratory infectious disease of the susceptible population, the accuracy of the risk assessment is improved, and the public security is better ensured.