Abstract: Inertia-ratio is an important feature for mid-course ballistic target recognition. It’s necessary to know the ballistic target’s to calculate the Inertia-ratio precession parameters. But estimating the precession parameters of cone-cylinder ballistic target needs to know some of its structure parameters. Firstly, this paper analyzes the procession feature of the cone-cylinder ballistic target and its High Range Resolution Profiles (HRRPs). Then based on the analysis of the precession of cone-cylinder target, the ‘Pseudo-inertia-ratio’ feature is proposed, which can be estimated without knowing the structure parameters of the cone-cylinder target. And the method and steps to extract the ‘Pseudo-Inertia-ratio’ feature based on HRRPs are presented. Finally the simulation results are given to validate that the ‘pseudo-Inertia-ratio’ feature and the presented method are effective and applicable.