The measurement accuracy of wind direction and wind speed is very important to the unmanned sailboat control, but the mature mechanical wind sensor and ultrasonic wind sensor both have great defects to be applied to the unmanned sailboat. Inspired by previous works on neural networks, we propose a low-cost, real-time, and robust wind measurement system based on computer vision (CV). This CV-wind-sensor includes an airflow rope and a camera, which can be simply deployed on the sailboat. We implement a prototype system on the FPGA platform and run a series of experiments that demonstrate the promising performance of our system. For example, the absolute measurement loss of the CV sensor in this paper is basically kept below 0.4 m/s, which shows a great advantage of measurement accuracy compared with the mechanical sensor.