Abstract-Since the system-level package was proposed, the electronics industry has increasingly attached importance to both directly relevant and related issues, and the scope of system-level package usage has increased. Creating more complex systemlevel package structures, thereby leading to the design of overall electrical effects, requires more electromagnetic simulation resources, and therefore a great deal of time in the design process. The main purpose of this paper is to analyze the effects of system-level packaging, and to establish systems-in-package in accordance with electrical specifications. Using a segmented approach, this paper also builds an overall model for designers to predict electrical characteristics, thus shortening the product development schedule. In this paper, the transmission effects of a substrate are analyzed by changing the length of the substrate transmission line, with or without a thermal ground ball and ground ring. Previously established package IP are cascaded to establish the model of the package substrate, which verifies the feasibility of the package IP. We then analyze the characteristics of the interference between chips and package using an integrated passive device, and propose a complete package equivalent circuit model.