We have found that the influence of polarizing direction of pumping pulse on the pulse width of synchronously pumped and mode-locked dye laser light in three solvents with different viscosities is proportional to the viscosities of the dye solvents. When’ the polarizing direction of the pumping pulse is parallel with the permitted direction of the dye laser, the laser pulse width would be shorter as the viscosity of the dye solvent is higher.