<p>The cyber security situation rating (CSSR) method and its stability analysis is key problems in nowadays cyber security. However, the existing CSSR methods do not take into account to the issues such as the fuzziness and hesitation of the grades of attributes, the non-compensation of information among attributes, the internal differences of attributes and the stability of CSSR method. A new piecewise variable weight&#xa0;rating (PVWR) method for CSS is proposed, and then the stability analysis for the PVWR method is researched. Based on the description of the CSS rating problem, linear membership functions (LMFs) and linear non-membership functions (LNMFs) of attributes with four categories grade threshold are constructed. The definition of PVWR function is proposed to more accurately reflect the characteristics of CSS, which is constructed by continuous piecewise function. A novel stability analysis of the PVWR method is proposed, and the attributes’ weight ranges under the condition of the current grade assessment is given when the CSSRM results is stable. The proposed method not only offers a novel method to identify the key impact attributes, but also provides theory basic for judging whether CSSR results have changed.</p>