A method for determining the empty state of an IV bottle is provided in an IV infusion monitoring device or in a networking monitoring system, which is cable to monitor the infusion data during whole infusion process. The infusion data includes the weight of remaining medical liquid in the IV bottle, the infusion rate and the remaining time from completion as well as the empty state. It also gives alarm as the measured gross weight of the IV bottle drops to the empty state. The empty state is determined preferably in terms of necking effect and needle tip effect, or their combination.