According to the temperature tenability of chirped fiber grating, the minimum output pulse width can be obtained by controlling the fiber grating’s temperature to change the dispersion of the chirped fiber grating, and the feasibility of this idea is demonstrated through experiments. The chirped fiber grating is used as the stretcher in the fiber chirped pulse amplification (CPA) system, and the gratings-pair is used as compressor. The positive dispersion brought by the stretcher is compensated by the negative dispersion provided by the compressor. The output pulse width is measured by the auto-correlation for denoting the dispersion of the chirped fiber Bragg grating indirectly as a function of temperature. It can be seen from the obtained experimental data that, when the temperature rises from -7 ℃ to 50 ℃, the pulse width falls from 1057 fs to 764 fs, and then rises to 910 fs, with a total change of 439 fs achieved. In the experiment, dispersion increases with temperature rising, changing from insufficient dispersion compensation to over dispersion compensation.