A new resonant diaphragm liquid density sensor based on resonance principle is designed due to the need of the real-time online measurement for fuel quantity during aircraft flight. On basis of analyzing the mathematical models of resonant diaphragm

a integral structure of resonant diaphragm density sensor is designed based on the method of digital closed-loop. Experiment results show that the sensor has high precision， good stability，simple structure

easy processing and can meet the demand of real-time online measurement for aircraft kerosene.