In this paper, we design a LabVIEW-based UAV online monitoring and safety situation assessment system to address the deficiencies in the monitoring of UAV flight state parameters and safety situation assessment. The system includes a lower computer recorded by the UAV and an upper computer on the ground. The lower computer collects and detects the flight data and connects to the upper computer through the serial port via the wireless digital transmission module, and the upper computer receives the data and carries out the monitoring of the UAV and the estimation of the safety situation. The lower unit of the system adopts multi-sensors to collect UAV navigation information in real time to achieve flight detection, and the upper unit adopts LabVIEW to design UAV online monitoring and safety situation estimation system to achieve monitoring and safety situation estimation during UAV navigation. The test results show that the system is able to detect and comprehensively display the navigation information of the UAV in real time and realize the safety situation assessment and alarm function of the UAV, which can realize the functions of online monitoring and safety situation assessment during the navigation process of the UAV.