In this paper, the influence of windows was analyzed on thermal ventilation in workshop. The influence was also numerically simulated by k-epsilon turbulance model and CFD software. In designing natural ventilation, to coordinate the dimensiom, between the inlet and owlet openings and to play down the neutral plane properly may be the effective measures to increase ventilation efficiency. In supervising ventilation, the cooperation should be intensified between the inlet windows, the upper-side windows and elerestories in order that airflow short-circuit, may be avoided, The simulation results...