Abstract: Carrot is a kind of familiar vegetable, and it has abundant carotenoid content. Carrot grinding is a common processing method. In this paper, the changes of the influencing factors including the powder particle size, the temperature, the moisture content and the carotenoid content in the grinding process were researched through the carrot shearing and crushing tests. The evaluation index of powder particle size was the percentage of particle size which was less than 125 μm, screened by standard sieve whose mesh number was 120. Through the single factor test, the result showed that the percentage of particle size less 125 μm decreased first, then increased and later decreased once again during the crush time of from 1 to 5 min. According to the references and the analysis results, the main reason of percentage decreasing was powder reunion. When the crush time changed from 1 to 4 min, the average temperature increased by 40.2 ℃, measured by Testo 890-1 infrared thermal imager, and the moisture content increased by 1.658%, tested by drying oven. The percentage of particle size which was less than 125 μm decreased by 7.17%, as crush time changed from 4 to 5 min. Otherwise, the carotenoid content of carrot powder decreased by 228 mg/kg due to the high temperature produced in crushing process. It was found that the main reason of powder reunion was that the surface forces among particles increased with the rise of the particle specific surface area, the temperature and the moisture content. The main surface forces among particles included: Van der Waals force, which increases with the growing smaller of particle size, electrostatic force, which is a result of friction, and hydrogen bonding force, which is made by moisture in powder. In consequence, the most effective method to solve the reunion of powder was to reduce the surface forces among particles. High voltage electrical field can overcome the surface forces among particles so that the powders have capability of resisting reunion. In this study, according to "Asakawa effect" and the principle of needle-plate electrode, the test device of high voltage electrical field was designed. The test device of high voltage electrical field could form a non-uniform electric field that was used to treat carrot powder. The treating voltage and the treating time were the test factors, and the percentage of particle size less than 125 μm was the evaluation index in the single factor test and the orthogonal experiment. Then, the regression equation was established and optimized. The test factors' significant order for the evaluation index was: treating voltage> treating time> treating voltage× treating time> treating time2. Based on the linear programming theory, the optimal processing parameters were determined. The appropriate treating voltage was 45 kV, and the best treating time was 60 min. Through the verification test, the percentage of particle size less than 125 μm was increased from 61.75% to 77.38%. The conclusions of this study provide a theoretical reference for the efficient processing of carrot powders.