针对海水折射率变化引起差分激光三角法溢油油膜厚度测量系统结果误差增大的问题，理论分析了海水折射率变化对厚度测量值的影响机理，研究了折射率变化与测量结果误差大小的关系。提出了基于二维曲面拟合的误差补偿方法。该方法通过采集不同厚度、不同折射率下的厚度测量值，利用二次多项式曲面拟合建立测量误差、厚度测量值和折射率之间的函数关系，根据测量值和折射率值，就可得到误差补偿值，进而实现对测量结果的补偿。通过对不同折射率、不同厚度陶瓷量块的补偿实验，结果表明补偿后的厚度测量值更接近真值，测量结果的误差显著降低。

The analysis on the seawater refractive index which increases the error of oil film thickness measured by differential laser triangulation are taken to discover the relationship between the change of refractive index and error. Accordingly a method based on two-dimensional curved surface fitting is proposed to compensate the error. The data of thickness are measured in the water of different refractive indexes and the quadratic polynomial curved surface fitting is adopted to formulate the error, thickness and refractive index. Then the measurement of thickness is compensated by using the above the formula and the refractive index. The experiments taken on different refractive indexes show the thickness measurement compensated is closer to the true value and the error is minimized.