Objective To evaluate the effect of different ventilation modes on the diffusion of person's cough droplet nuclei in the elevator under the background of coronavirus disease 2019 epidemic. Methods Based on the computational fluid dynamics (CFD) gas-solid two-phase flow, Realizable K-ε turbulence model and particle trajectory model were used to study the diffusion process of droplet nuclei generated by person's cough in the elevator within 10 seconds, airflow velocity variation, droplet nuclei diffusion characteristics and concentration distribution of three kinds of ventilation at elevator top (the rear, both sides and four corners ventilation) were compared, risk on person was analyzed. Results Within 10 seconds, the number of airflow velocity vortex gradually decreased under the condition of ventilation at the rear and both sides, while increased when ventilation was at the four corners; droplet nuclei moved with the airflow in an inverted "S" shape trajectory when ventilation was at the rear, droplet nuclei moved up and down with the airflow when ventilation was at both sides, droplet nuclei presented a "C" shape trajectory when ventilation was at four corner. After 10 seconds, the increase of ventilation could quickly reduce the droplet nuclei concentration by 90%. Conclusion The opposite side of the droplet releaser is the high-risk area of contacting with the bacteria-carrying droplet nuclei. Although four corner ventilation can quickly dilute the overall droplet nuclear concentration, risk of infection can be increased if there is droplet releaser who is at the oblique opposite. Ventilation site should also be considered when ventilation volume increases, so as to reduce the risk of personnel infection.