The invention relates to an oil-gas pipeline online stress ultrasonic measurement device which comprises a processor, an ultrasonic transmitting module, an ultrasonic receiving module, a time measuring circuit module, a liquid crystal display and interaction module, and a power management module. The ultrasonic transmitting module transmits a high-voltage pulse. The ultrasonic receiving module receives signal waveform amplifying and shaping. The time measuring circuit module measures the time interval between a start signal and an end signal of ultrasonic transmission. The liquid crystal display and interaction module is used for system management and measurement result display. The power management module supplies power to the processor, the ultrasonic transmitting module, the ultrasonic receiving module, the time measuring circuit module and the liquid crystal display and interaction module. The processor is used for managing the system, controlling the power supply, collecting a measurement result, processing the measurement result and making the result displayed. The detection accuracy is improved. Electromagnetic interference is prevented. The system can work in the field continuously, steadily and stably for a long time. External interference is isolated. The measurement result is real and reliable.