With the continuous increase in the transmission rate of high-speed data transmission lines, how to use the S parameters familiar to microwave circuit engineers to characterize the time-domain eye diagrams familiar to digital circuit engineers has become a problem that measurement engineers must solve in the context of impedance matching and bandwidth issues for high-speed digital transmission lines. This paper designs a measurement and characterization method for high-speed data transmission lines, which uses a multi-port vector network analyzer to measure and characterize the transmission characteristics of high-speed data transmission lines, establishing a direct correspondence between the S parameters familiar to microwave circuit engineers and the eye diagrams familiar to digital circuit engineers. By using a multi-port vector network analyzer to measure the frequency-domain S parameters of multi-channel data transmission lines, including the reflection S parameters, transmission S parameters, and crosstalk S parameters of the data transmission lines, the frequency-domain modeling of multi-channel data transmission lines is achieved. Through the inverse Fourier transform of the frequency-domain reflection S parameters, transmission S parameters, and crosstalk S parameters of multi-channel data transmission lines, the time-domain reflection, transmission, and crosstalk impulse responses of multi-channel data transmission lines are obtained. Assuming that an ideal error-free digital signal is input to a nonideal multi-channel data transmission line, the output digital signal of the multi-channel data transmission line can be obtained through the convolution of the input digital signal and the impulse response, thereby obtaining the eye diagram familiar to digital circuit engineers and achieving the time-domain modeling of multi-channel data transmission lines.Taking the frequency domain and time domain performance characteristic measurement and characterization of HDMI data transmission lines as the application scenario, a test fixture for HDMI data transmission lines was fabricated. The time domain reflection, transmission and crosstalk eye diagrams of HDMI data transmission lines were measured, and the experimental results were presented. From the measured time domain eye diagrams, it can be seen that as the transmission rate increases, the transmission quality of HDMI data transmission lines deteriorates. When the output rate is 5 Gb/s, the time domain eye diagram is relatively clear, and the digital transmission line can complete the transmission task well. When the digital transmission rate is 10 Gb/s, the time domain eye diagram is already blurred and unclear, and cannot complete the digital signal transmission. This verifies the effectiveness and accuracy of the data transmission line measurement and characterization method. The traditional eye diagram measurement of digital storage oscilloscopes and sampling oscilloscopes requires separate measurements of the input and output eye diagrams, followed by manual comparison to determine the signal transmission quality of the transmission line. The measurement and characterization method proposed in this paper directly measures the reflection, transmission, and crosstalk eye diagrams of digital transmission lines, directly reflecting the signal transmission quality of the transmission line. This solves the measurement and characterization difficulties of high-speed digital transmission lines and is of great significance for the measurement and characterization of digital transmission in fields such as high-speed digital communication, computing power networks, and mobile communication.