Generation of high energy sub-picosecond laser pulse was demonstrated in the Nd:glass chirped pulse amplification system. Seeded with pulse originating from OPA front end, the laser system output chirped pulse with maximum energy up to 168 J, and the spectral width was 5.5 nm （FWHM）， centering at 1054 nm. Systematic investigation showed the spectral width of pulses was about 4—6 nm with energy higher than 100 J, which supports high energy laser pulse with pulse duration less than 300 fs. The final pulse was compressed to as short as 710 fs by a mosaic grating compressor.