By adopting the numerical analysis method, a two-dimensional model of a large space plant with internal heat sources and vertical solar chimneys has thus been established, with the external expansion calculation domain added to analyze the influence of different ventilation opening modes and of different height width ratios of solar chimneys on the air distribution and airflow in the plant under natural ventilation conditions, followed by an analysis of the air flow velocity at each special location in the room in combination with the air age. The results show that the bottom-in and top-out opening method combined with an indoor hot pressure drive is characterized with a good effect on the internal ventilation of the plant. When the height-width ratio of the solar chimney is 1.00, the average indoor air distribution velocity is high in its value, with a low air age and the best gain effect.