| In this thesis,we shall use Yosida approximation to discuss the sta-bility of a class of stochastic partial differential equations with semi Markov switching . Our main results are as follows:(ⅰ)the existence and uniqueness of mild solutions are proved;(ⅱ)the processes of Markov and genenrators are given;(ⅲ)we obtain the sufficient conditions of exponential stability.Our results is an extension of existing results in [6]. |