理论上求解了高黏度流体表面波的色散方程，发现此类表面波随无量纲数Y值增大，存在一极值点Y≈0.145，跨越该点时表面波的弛豫特征由指数衰减转变为振荡衰减，同时流体表面波的色散方程也发生根本变化。为了验证上述推论的正确性，利用表面光散射法研究了温度在286.27~373.32 K范围内时高黏度流体邻苯二甲酸二异癸酯(DIDP)的弛豫特征和黏-温特性。结果表明：Y值随温度升高而减小，当Y<0.145时，表面波以指数形式衰减且不传播，此时黏度测量值与文献值的平均偏差不超过±1.5%；当Y>0.145时，表面波以振荡衰减形式传播，此时黏度测量值与文献值的平均偏差不超过±2%；当Y→0.145时，黏度测量偏差急剧增大，不能可靠地获得流体黏度。研究结果有助于认识高黏度流体表面波的弛豫特征，为利用表面光散射法精确、可靠地测量高黏度流体黏度奠定了基础。

The present work solves the dispersion equation for high viscous fluid surface waves. It is found that the relaxation characteristics of surface waves change from exponential decay to oscillation decay, and the dispersion equation for fluid surface waves makes a fundamental change when the waves step over the extreme point (Y ≈ 0.145) with the increasing of dimensionless number Y. To verify the correctness of the proposed result, the relaxation and viscosity-temperature characteristics of fluid di iso decyl phthalate (DIDP) with high viscosity fluid by using surface light scattering method while the temperature is in the range of 286.27-373.32 K. The results show that Y value decreases with the increase of the temperature. When Y<0.145, surface waves decay in exponential form and do not spread. The average deviation of measured viscosity and the viscosity in the reference is within ±1.5%. When Y>0.145, surface waves spread with oscillation decay form. The average deviation of measured viscosity and the viscosity in the reference is within ±2%. When Y→0.145, measured viscosity deviation increases sharply, and we cannot get reliable fluid viscosity. The present work will be helpful to understand the relaxation characteristics of high viscous fluid surface wave and offer the theoretical background for accurate and reliable measurement of the viscosity of high viscous fluid with surface light scattering method.