The problem of integration and detection of range spread target in colored Gaussian noise is studied. A new method of continuous range profiles' detection is proposed. As the fourth-order cumulant has a good function to restrain Gaussian noise, we regard the fourth-order cumulant's solution as a kind of nonlinear transform and get a new integration between frames. Both the analysis of theory and the result of simulation show that this algorithm has a better performance than usual algorithm of energy integrating detection for the integration of continuous range profiles