Influence of air dispersion on the pulse width is studied in the distance measurement of femtosecond pulsed laser. The femtosecond pulsed width variations with input femtosecond pulsed width, central wavelength and the propagation distances are given in analysis. Compensation scheme of air dispersion based on high-density transmissive grating is put forward to maintain distance measurement accuracy. Then influence on compression of femtosecond pulsed laser width by grating period and distance is also given. The method has some advantages, such as compact volume and convenient operation. It will be helpful for high-accuracy long distance measurement by using femtosecond laser.