Abstract: Temperature significantly influences the monitoring data from vibrating wire strain gauges (VWSGs) in tunnel engineering. Based on the working principle and on thermal response characteristics of VWSGs, this study systematically investigates the mechanism of temperature-induced errors. A temperature error model is thusly established to clarify the relationship among the monitored strain, true strain, mechanical strain, and thermal strain. A novel approach using segmented fitting and mean statistics is proposed to determine temperature correction coefficients for VWSGs. Research results indicate that the monitored strain primarily reflects steel wire tension rather than true structural strain. The temperature-related component in the monitoring data stems from the difference in thermal expansion coefficients between the structure and the steel wire, representing measurement error devoid of physical significance. Therefore, directly converting the monitored strain into structural stress is inaccurate. Due to structural constraints, temperature correction coefficients vary depending on sensor location and type. Coefficients derived from laboratory conditions show limited applicability in the field, necessitating individualized correction for each sensor. The correction method proposed effectively separates temperature-induced errors from the monitoring data and outperforms conventional correction techniques, as well as methods such as principal component analysis, wavelet transform, and empirical mode decomposition. Temperature-induced errors are found to account for approximately 25% of monitored strain in tunnel engineering, highlighting the essential role of error correction in structural health monitoring.