Friction stir welding is a coupling process involving many physical fields. Therefore, it is necessary to collect and study temperature signals, acoustic emission signals and vibration signals in this process. The design and development of online detection system for friction stir welding based on LabVIEW virtual instrument technology was introduced in detail. The main hardware included Advantech PCI1714 data acquisition card, infrared temperature sensor, acoustic emission sensor, acceleration sensor and its corresponding signal conditioning and amplification circuit. The system can realize a variety of signal data acquisition, data processing, realtime display and data storage. By 7022 aluminum alloy welding experiments,the reliability and accuracy of the system are verified. It provides experimental basis for the construction of the welding processing system to predict.