Femtosecond laser has many potential applications in various fields, such as industrial processing, precision measurement, defense, and scientific research. A high-power and high-pulse-quality femtosecond chirped-pulse amplifier system based on spectrum control and dispersion optimization is reported. In the proposed system, the chirped fiber Bragg grating (CFBG) with tunable dispersion is designed to match the compressor and can be fine-tuned. Thus, the net dispersion of the system approaches zero by controlling the residual dispersion of CFBG dispersion compensation system. Furthermore, the degradation of the pulse quality in the amplification processing is avoided by controlling the spectral shape via spectral filtering before the main amplifier to prevent distortion. Finally, high-quality femtosecond laser pulses as short as 198 fs with an average power of 24 W at a repetition rate of 50 MHz are generated.