The spectrum width is expanded from 38 nm to 66 nm, and the output laser pulse is consequently squeezed from 35 fs to 20 fs in the 10 Hz femtosecond regenerative amplifier, with an acoustic-optic programmable dispersive filter(AOPDF) for dispersion pre-compensation and spectrum shaping of the input seed pulses. The experimental results show that the AOPDF can make spectrum shaping and dispersion compensation in a large range simultaneously and independently, depress effectively the spectrum gain narrowing in the chirped pulse amplification and compensate the residual dispersion in the Ti∶sapphire laser system. The result paves the way for the development for 20 fs, 10 TW Ti∶sapphire laser.