Theoretical analysis of the reflective characteristics of paraboloidal mirrors has shown that the cross─section intercepted by the cone of light reflected from any point of the parabola with the focal plane would be respectively a circle,ellipse parabola,hyperbola or two cross lines.Based on the interception profile on the focal plane an inprovement on the design of reflective so- lar cooker is proposed:(1)to in increase the angle of collection;(2)to choose the reflective curve mirror properly.