A method to design a birefringent plate (BP) for broadening spectrum in a regenerative amplifier is presented. Using this method, we design a quartz BP with thickness of 761 microns inserted into a Ti:sapphire regenerative amplifier. The gain narrowing effect is reduced efficiently, and the experimental results agree with the calculation well. The bandwidth is broadened from 28 to 62 nm using the designed quartz BP and the pulses are compressed to ~23 fs.