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.