将修正的TTHG(two term Henyey-Greenstein)散射相位函数运用到电子散射理论中，并利用小角度近似条件推导出沙尘天气下激光信号脉冲时延和展宽的表达式。研究了脉冲时延、展宽与沙尘能见度之间的关系，以及散射反照率、散射系数和不对称因子等因素对脉冲时延和展宽的影响；分析了不同波长条件下脉冲时延和展宽随传输距离的变化规律。结果表明，在能见度较低的沙尘天气下，脉冲的时延量和展宽量均随传输距离、反照率和散射系数的增大而增大，随大气能见度的增大而减小。尤其是当大气能见度增加至3.5 km时，脉冲时延和展宽逐渐趋于一个与激光波长有关的稳定值。随着激光信号波长和沙粒不对称因子的增大，脉冲的时延和展宽呈负指数趋势减小。

Expressions of laser signal pulse delay and broadening in the sand and dust weather are derived when we use the small angle approximation and apply the modified two term Henyey-Greenstein (TTHG) scattering phase function to the electron scattering theory. Variations in pulse delay and broadening with atmospheric visibility, and the effects of scattering albedo, scattering coefficient and asymmetric factor on pulse delay and broadening are studied. Moreover, the changes of pulse delay and broadening with transmission distance under different wavelengths are analyzed. The results show that in the sand and dust weather with low visibility, the pulse delay and the broadening increase with the increasing of transmission distance, scattering albedo and scattering coefficient, and decrease with the increasing of atmospheric visibility. Particularly, when the atmospheric visibility increases to 3.5 km, the pulse delay and the broadening gradually approach to wavelength-related stable values. In addition, with the increasing of laser signal wavelength and sand asymmetric factor, the decreasing of pulse delay and broadening follows the negative exponential distribution.