This paper presents some preliminary results on robust stability analysis of positive systems. A general analysis framework with Integral Quadratic Constraints (IQC) is refined for nonnegative uncertain systems. Based on this framework, a new approach for robust control design is proposed. The new framework not only enables a stability analysis of a positive systems, but also suggests new robust control design strategy for systems which has nothing to do with the positive systems at first glance. An example is shown in which such a control design method provides a sharper result than the control design using existing IQC techniques.