The portable (handheld) radar flowmeter uses K-band radio waves for non-contact velocity measurement of rivers, sewage, mud, and oceans. The instrument is compact in size, handheld in operation, and easy to use. Not corroded by sewage or disturbed by sediment, it can be widely used in fields such as field patrols, flood control, and sewage monitoring. Especially suitable for monitoring during flood season and emergency situations;