Abstract: The problem of estimating the number of goods in the warehouse is studied by RFID technology. The information transmission between active tags and readers consume the energy of batteries. But recharging batteries for tens of thousands of tags is laborious. Hence, energy conservation is a very important direction in this field. So, an algorithm is proposed to reduce the amount of energy consumed by active tags during the process of estimating the number of tags in a system and make the energy consumption of each tag is approximately balanceable. Through the simulation results, we can draw the conclusion that it achieves good results, and it can bring great convenience for the development of storage industry.