Under vibrating action of the seed-feeding box, flat solanaceous vegetable seeds would gather with disordered position and attitude around suction holes of the pneumatic drum seeder because of their poor flowability. That would result in high multiple-seed rate during precision sowing for flat solanaceous vegetable seeds. Therefore, a directional vibrating seed-feeding device with a Y-shaped guide groove was designed. Based on theoretical motion analysis of the seed on the vibrating seed-feeding device, installation angle of the seed guide plate was designed to be 10°, and the vibration direction angle of the seed guide plate was determined to be 25°. Through vibrating test, the amplitude-frequency characteristics of the seed guide plate excited by a linear electromagnetic vibrator was obtained. By means of high-speed photograph method, the Chaotian pepper seed was tested to study influence of different vibration intensities on seed flow characteristics in the guide groove of the seed-feeding device. The results showed that with th increase of the vibrating voltage, the vibration frequency of each detection point remained at 100Hz, the vibrating amplitude of the seed guide plate along X, Y and Z directions was increased, and flow velocity of the seed along Y direction relative to the guide groove was increased. When the vibrating amplitude of the seed guide plate along Y direction was in the range of 0.45~0.54m, the seeds in a guide groove can form uniform single layer distribution, and the seed flow velocity of each guide groove had better consistency. In order to verify the effect of the directional vibrating seed-feeding device, a contrast sowing test was conducted. The results showed that by utilizing the directional vibrating seed-feeding device, at the efficiency of 300 tray per hour, 600 tray per hour and 900 tray per hour, the sowing qualified seed rate of Chaotian pepper was more than 95%, and the seed-missing rate was less than 5%. It showed that the designed directional vibrating seed-feeding device can significantly improve the qualified seed rate, reduce the multi-seed rate and meet the precision seeding requirements for flat pepper seed.