The present invention discloses a signal compensation method and device. The method includes: receiving an input signal sequence suffering from ISI interference, and using a first filtering coefficient to perform filtering compensation on the received signal sequence, to obtain a first compensation signal sequence; using a balance filtering coefficient to perform filtering compensation on the first compensation signal sequence, to obtain a balance compensation result, where the balance filtering coefficient is obtained by adjusting, according to a first compensation error, a balance filtering coefficient used last time; and performing sequence estimation on the received balance compensation result and outputting the balance compensation result. A first compensation error is generated by a back-end compensation module, the first compensation error is used to adjust a balance filtering coefficient in an iterative manner, and the balance filtering coefficient is used to perform filtering compensation on a first compensation signal sequence, thereby effectively compensating for a signal sequence suffering from ISI interference, and improving performance of an optical fiber communications system.