— Many real-world dynamic optimisation problems have constraints, and in certain cases not only the objective function changes over time, but the constraints also change as well. However, in academic research there is not many research on continuous dynamic constrained optimization, and particularly there is little research on whether current numerical dynamic optimization algorithms would work well in dynamic constrained environments nor there is any numerical dynamic constrained benchmark problems. In this paper, we rstly investigate the characteristics that might make a dynamic constrained problems dif cult to solve by existing dynamic optimization algorithms. We then introduce a set of numerical dynamic benchmark problems with these characteristics. To verify our hypothesis about the dif culty of these problems, we tested several canonical dynamic optimization algorithms on the proposed benchmarks. The test results con rm that dynamic constrained problems do have special characte...