Abstract: To explore the application of particle image velocimetry (PIV) technique in the experimental investigation of fiber-reinforced polymer (FRP)-confined circular concrete columns, and to assess the reliability and accuracy of this technique, this study employs both PIV technique and conventional foil strain gauges to characterize the strain behavior of FRP-confined concrete specimens under axial compression. A series of factors influencing the PIV analysis results were systematically examined. The results demonstrate that PIV technique can accurately characterize the stress-strain behavior of FRP-confined concrete columns. Compared to foil strain gauges, the average percentage error between the two methods was −2.89%, indicating that PIV technique exhibits sufficient reliability. Additionally, variations in subset size and location have negligible impact on the PIV results. By implementing virtual strain gauges of different lengths, the PIV technique effectively captures both local and average strain responses of the specimens with considerable accuracy.