This paper presents a reduced order modeling method of inverter-based microgrid for stability analysis. The full order model of microgrid with three inverter-based distributed generations (DGs) is derived. Then singular perturbation method is applied to reduce the full order model. The dynamic system is divided into two subsystems based on the participation analysis of the original model. The states that have considerable effect on the dominant dynamics are preserved, and the states with negligible impact on dominant dynamics are eliminated. The reduced order model is verified by comparing original model and reduced models for numerical simulation and eigenvalue analysis.