The problem of interaction of microwaves with plasma is complicated and has garnered considerable interest. Parameters of plasma density, collision frequency, and plasma size have been shown to exert substantial impacts on microwave transmission in plasma. The respective influences of plasma parameters can be evaluated relatively easily; however, plasma must also be considered integrally as it is an electrically neutral medium. In this paper, using a designed plasma-metal model, we assess how plasma parameters influence the interaction of microwaves in plasma, revealing a nonmonotonic and complex relationship. Using parameter optimization, we obtain plasma parameters for plasma device design that meet the requirements of microwave transmission in plasma; the findings should prove useful in applications of electromagnetic waves in plasma.