A two-dimensional numerical model was presented for simulating the fluid flow during the bio-venting remediation process.The axis symmetry contaminated zone with a single vertical injection well was used for this simulation.The changes of fluid fields with time were obtained and the results from simulation showed that fluid field changed greatly in the first 30 min，and the change became smaller from 30 min to 60 min. After 60 min，nearly no change was obtained.The required time to develop the steady fluid fields was about 60 min with air injection rates of 81.504 m3·d-1 and 407.52 m3·d-1.The transport，mass transfer and biodegradation of contaminants could be simulated in follow-up studies based on the results of the flow modeling.