考虑连续系统的一类混合Ｈ２／Ｈ∞控制问题，对于含无穷远零点和有限虚轴零点的奇异广义对象，引入线性矩阵不等式（ＬＭＩ）方法研究了降阶控制器存在判据和设计准则．文中指出，对于所述对象，若混合Ｈ２／Ｈ∞控制问题可解，则它必存在降阶控制器．存在准则和设计方法分别归结到ＬＭＩ的可解性及其凸优化解法 Considering a class of mixed H2 / H∞ control problems for continuous systems, the existence criterion and design criteria of reduced order controllers are introduced for linear singular generalized objects with infinite zeros and finite imaginary axes zeros. It is pointed out in the paper that if the mixed H2 / H∞ control problem is solvable for the object, then it must have a reduced order controller. The existence criterion and design method are respectively attributed to the solvability of LMI and its convex optimization solution