The particle flow velocity is an important parameter of gas-solid two-phase flow. This paper presents a new method for measuring solid particle velocity based on planar array capacitive sensors. Firstly, the 3D electromagnetic field simulation software Ansoft is used to model the sensor, and the spatial axial sensitivity is obtained. Based on the distribution of the axial sensitivity, the spatial filtering characteristic of planar array capacitive sensors is investigated, and the mathematical expression of the velocity measurement is derived. Then a measurement system based on planar array capacitive sensor for measuring the velocity of solid particles is designed and experimentally evaluated on the gravity transport experimental device. The experimental results indicate that the particle velocity is linear with the spectral width of the sensor output signal when the particle flow velocity is between 1 m/ s and 3 m/ s. The relative error of the velocity measurement is less than 9%, and the repeatability error of the test system is within 11%.