Why companies prefer conservative capital structure? Based on the theory of financial flexibility, and choosing the recently financial crisis as study event, this paper, empirically investigates the impacts of conservative capital structure preserved during the pre-crisis period on corporate investment behaviors in crisis. The results show that: during the pre-crisis period, companies maintaining conservative capital structure invest relatively less, and control companies invest relatively more. While in the crisis period, companies with conservative capital structure have greater capacity to raise debt funds, and greatly increase their investment expenditures, which mainly depend on their growth opportunities. In contrast, control companies rely much on the internal cash flow to support their investment expenditures, which reduced substantially as a result. In general, the empirical evidence provided in the paper supports the view that, companies can establish financial flexibility by maintaining conservative capital structure, so as to handle adverse shocks more effectively. And this also offers some useful empirical evidences for corporate capital structure decision.