This paper proposed a multiple-mode animal behavior analysis system integrating a wireless bio-potential recorder and two 120fps video streams. A 16-channel analog-front-end (AFE) featuring a chopper low noise amplifier (LNA) and a 12-bit successive approximation analog-to-digital converter (SAR ADC) is designed as the sensor interface. Bluetooth Low Energy (BLE) based in-the-air protocol is implemented for wireless data transmission. A precise synchronization method is proposed featuring a millisecond level synchronization accuracy between the video frames and the acquired bio-potential. The compact wireless bio-potential recorder features a size of 2 × 2.5 × 1cm and a battery life of 9 hours. In-vivo test has been performed on rats with long-term implantable electrodes. The proposed system successfully recorded the ENG signal from sciatic nerves and EMG signal from leg muscles. And video-based gait analysis was performed and provided the labels to train an EMG-based gait phase classifier.