This paper investigates the problem of unmanned aerial vehicle (UAV) recognition in the presence of WiFi interference using passive radio frequency (RF) detection. The proposed method relies on machine learning based RF recognition and considers the scenario in the bandwidth of the video signal (VS) and WiFi are identical. Our machine learning strategy involves extracting 31 features from the WiFi signal and the UAV VS, which are then input to the classifier. Among the 31 features, 30 are statistical in the time and frequency domain, while the remaining one involves the effective subcarrier feature. We evaluate four different machine learning (ML) classifier variants and demonstrate through simulation and experiments that the proposed method can accurately recognize UAV VS in the presence of WiFi interference. We also improve the feature-vector compactness and reduce the 31-feature vector to a 6-feature vector composed of the most significant features and demonstrate that the recognition performance of random forest method (RandF) classifier is not compromised. The RandF obtains the best result, which has a recognition rate of 100% in the indoor experiment. While in the 2 km outdoor experiment, the recognition rate of the four ML classifiers is larger than 95.52%, which is better than other UAV detection methods such as radar, acoustic and video.INDEX TERMS UAV video signal, recognition, WiFi interference, machine learning.Ming Zuo Author received Bachelor's degree in Communication Engineering from Jiangxi Normal University, Nanchang, China, in 2014, and he Master's degree in Electronic and Communication Engineering from Nanchang University, Nanchang, China, in 2016. He is currently pursuing the PHD degree with the School of Electronic and Information Engineering, Beihang University. His research interests focus on radar signal processing, electronic countermeasure, passive positioning, anti-unmanned aerial vehicles.