The research on chirp linearization of a semiconductor laser using an optoelectronic feedback loop is reported. Self-homodyne detection is adopted to characterize the chirp nonlinearities. The beat signal is fed to a frequency discriminator circuit, which measures the laser instantaneous frequency deviation from a perfectly linear chirp and provides an error signal. The error signal is fed back to the modulation current of the laser, and thus an optoelectronic feedback loop is achieved and linear tuning is realized. The experiment is conducted with a 1550 nm distributed feed back (DFB) laser. The injection current is modulated by a ramp with 20 mA in amplitude and 30 ms in period. A linear tuning range of 10 GHz is realized in experiment. The system is both stable and effective. This technique is of significance to applications such as frequency-modulated continuous-wave laser radar, optical frequency-domain reflectometry etc.