Abstract: High-speed rapeseed sowing has been confined to the high seed flow, low detection accuracy, and short battery life. In this article, a solar-powered device was proposed to detect the high-speed seed flow during rapeseed sowing, in order to improve the sowing efficiency and quality. Multiple channels of seed flow falling and synchronous detection were achieved during high-speed sowing. According to the requirements of agronomy and detection accuracy, 8 low-flux seed flows were divided during high-speed sowing. An 8-channel diversion structure was then designed to independently detect the seed flow. The photoelectric technologies were adopted to combine with the LED array light source and silicon photocell structure. A ring circuit board was integrated with eight channels using surface mount technology. The signal was accurately processed in each channel. Each circuit board was integrated with the detection functions, in order to monitor the status of seed flow in real time. The data support was then offered for the precise control of seeding operations. Furthermore, the optimal parameters were selected to design a boost circuit and solar charging control module in the solar panels. These components together formed an efficient solar energy system, providing a stable energy supply for the detection device. A series of tests were carried out to determine the parameters of each key component in the system. The high reliability and stability were then obtained after optimization. The bench test showed that the accuracy of the 8-channel device was achieved above 97.53% to detect the rapeseed sowing amount, which was 10.03 percentage points higher than the original 4-channel when the sowing frequency of rapeseed seeds was in the range of 60-130 Hz. The performance of detection was significantly better than that of the single- and 4-channel devices. Road tests show that the accuracy of the detection device for the rapeseed sowing rate remained stable at over 97.53% at the operating speeds of 10.3-15.7 km/h (78.9-123.5 Hz). Further field experiments verified that the accuracy of rapeseed sowing detection was not less than 97.07% at the high-speed operating speeds of 10.3-15.7 km/h (81.45-120.2 Hz). The sowing detection device was relatively stable. The accuracy of the detection was 0.46 percentage points lower in the field than on the road, due mainly to the influence of dust in the field. In terms of endurance time, the plug-in circuit board device worked continuously for 6 h, when powered only by a lithium battery. While the surface that mounted the circuit board device was worked for 7 h after optimization. After loading the solar energy, the device was achieved in the unlimited endurance on sunny and cloudy days. The endurance time also reached 72 h in the overcast weather. This finding can also provide data support for the precise detection of seed flow in high-speed rapeseed sowing, thus improving the endurance of the detection.