Clouds are the primary regulators of Earth's radiative balance, and ice clouds, composed of ice crystals, form in the upper atmosphere. Ice clouds have significant impacts on the atmosphere and weather. They reflect terrestrial heat during nighttime, leading to surface cooling. During the day, ice clouds can reflect solar radiation, reducing surface insolation and affecting temperature and climate. This paper investigates a millimeter-wave radar-based method for ice cloud detection. The study utilizes a millimeter-wave radar operating in the G-band, leveraging its high resolution and penetration capabilities in the high-frequency range to conduct ice cloud investigations. Firstly, we describe the millimeter-wave radar system, including its working principles, key parameters. Next, we present the formation mechanism and characteristics of ice clouds to better understand their scattering behavior with radar signals. Through research on ice cloud detection using millimeter-wave radar in the G-band, this study achieves a minimum detectable intensity of −40 dBz. This method provides an effective means to understand and predict the formation and evolution of ice clouds. It holds significant implications for disciplines such as meteorology, climatology, and environmental science, offering new perspectives and approaches for future ice cloud monitoring and forecasting.