In this paper, the biological droplet transport and deposition in the turbulent airflow inside an indoor environment was studied using the Lagrangian computational method. Meanwhile, as to the mathematic simulation, the Monte Carlo modeling method was coupled into this simulation program to describe the bio-particle transport. Many influent factors such as indoor airflow velocity, the bio-aerosol generator velocity, particle diameter, and evaporation and death were considered synthetically in this paper. Serratia marcescens was used as tracer microorganism to simulate the droplet nuclei exhaled by patients, and the spatial distribution of its concentration was measured. Collected bacteria were quantified using standard cultivating assays. It showed the simulation results were comparable with the data of the experimental findings.