In recent years, great advance has been made on electrostatic sensing technique for gas-solid flow measurement. Electrostatic tomography(EST) has been used in experiment researches as a novel non-intrusive measurement technique. Electrostatic sensor array is one of the key parts of electrostatic tomography system. Based on the image reconstruction algorithm, the charge on the particles can be obtained from the electrostatic measurement signals. However, reports on the relationship between the electrostatic signal acquired by the electrostatic sensor array and flow characteristics of the particles were very few. In this paper the mathematical model of the electrostatic sensor array was adopted, and its spatial sensitivity field was investigated. In the experiment, the electrostatic signals of the quarter flow and full pipe flow were acquired by the electrostatic sensor array. Based on the EST experiment and Power Spectrum Analysis of Signal, the energy distributions of those two flow patterns were compared...