This thesis takes walk-up apartments in Taiwan as an example and probes into the influence of Interior decoration on the effect on natural ventilation. Use literature review as the research method to look back on and arrange related documents in order to clarify the range draw up the method and assume the process. Apply case collection to gather cases printed in interior decoration magazines and try to comprehend the way of decoration of walk-up apartments. Besides, make use of numerical simulation to simulate and evaluate the effect of different ways of decoration on natural ventilation in order to put forth the ways of decoration with better natural ventilation to serve as the reference for practitioners in the related field when decorating.