In order to investigate the inherent polarization intensity in InGaN/GaN multiple quantum well (MQW) structures, the electroluminescence (EL) spectra of three samples with different GaN barrier thicknesses of 21.3 nm, 11.4 nm, and 6.5 nm are experimentally studied. All of the EL spectra present a similar blue-shift under the low-level current injection, and then tus to a red-shift tendency when the current increases to a specific value, which is defined as the tuing point. The value of this tuing point differs from one another for the three InGaN/GaN MQW samples. Sample A, which has the GaN barrier thickness of 21.3 nm, shows the highest current injection level at the tuing point as well as the largest value of blue-shift. It indicates that sample A has the maximum intensity of the polarization field. The red-shift of the ELspectra results from the vertical electron leakage in InGaN/GaN MQWs and the corresponding self-heating effect under the high-level current injection. As a result, it is an effective approach to evaluate the polarization field in the InGaN/GaN MQW structures by using the injection current level at the tuing point and the blue-shift of the EL spectra profiles.