Embodiments of the present invention disclose a method for implementing a compensation filter and an apparatus for signal bandwidth compensation. The apparatus includes: a digital predistortion filtering unit, a compensation filter, a conversion unit, and a power amplifier; where the digital predistortion filtering unit receives an original signal, performs predistortion processing on the original signal; the compensation filter receives the predistortion signal, compensates for distortion caused during a process of transmitting the predistortion signal to the power amplifier, and outputs a compensated predistortion signal to the conversion unit; the conversion unit receives the compensated predistortion signal, converts the compensated predistortion signal into an analog signal, performs frequency mixing processing, and outputs a predistortion signal experiencing the frequency mixing to the power amplifier; the power amplifier receives the predistortion signal experiencing the frequency mixing, amplifies the predistortion signal experiencing the frequency mixing, and outputs an amplified signal.