The two kinds of generalized gradient systems are proposed and the characteristics of the two systems are studied. The conditions under which the Nielsen equations can be considered as one of the two generalized gradient systems are obtained. The characteristics of the generalized gradient systems can be used to study the stability of solution of the Nielsen equations. Some examples are given to illustrate the application of the results.

%U https://xbna.pku.edu.cn/EN/10.13209/j.0479-8023.2016.078