Abstract: This study investigates the calibration method for ultrasonic Doppler string phantoms and presents the design and development of a calibration device based on intelligent technology. The device employs a dual-channel laser velocimeter to collect the rotational speeds of the drive and driven wheels of the ultrasonic string phantom. These data are then input into an analysis system to calculate the string velocity of the phantom. Additionally, the device can collect linear velocities at various points within the physiological waveform cycle and compare them with standard physiological waveform velocities in a database to determine whether the test waveform and physiological waveform curves meet requirements at the set velocity. Experimental results demonstrate that, compared to existing methods for detecting constant blood flow velocity, this method and device not only efficiently detect constant blood flow velocity but also intelligently assess physiological waveforms. This approach effectively addresses the calibration and traceability issues of ultrasonic string phantoms.