A nonlinear compensating apparatus, configured to perform pre-compensation for transmitting signals, comprising: an information sequence acquiring unit, configured to acquire a symbol information sequence of a pulse signal inputted by a transmitting side; a perturbation quantity acquiring unit, configured to acquire a perturbation quantity produced on a transmission link with a certain length and presented in form of the summation of weighted items, each item being a product of transmitting pulse information symbols at one or more moments relative to the current moment, and each item being weighted by a pre-obtained weighting coefficient corresponding to that item; characterized in that the nonlinear compensating apparatus further comprises: a perturbation quantity processing unit, configured to combine the items at the output of the perturbation quantity acquiring unit based on the weighting coefficients, so as to render a sum of combinations of addition and multiplication of symbols in a finite symbol set; and an information compensating unit, configured to calculate a difference between the symbol information sequence and the perturbation quantity at the output of the perturbation quantity processing unit to obtain a compensated symbol information sequence, so as to cause the transmitting side to transmit signals according to the compensated symbol information sequence, wherein the perturbation quantity processing unit is configured to combine the items to which the equal or approximately equal weighting coefficients correspond, or to combine the items to which the equal or approximately equal real parts of the weighting coefficients correspond, or to combine the items to which the equal or approximately equal imaginary parts of the weighting coefficients correspond, and wherein the perturbation quantity processing unit is configured to quantize the weighting coefficients before combining the items. an information sequence acquiring unit, configured to acquire a symbol information sequence of a pulse signal inputted by a transmitting side; a perturbation quantity acquiring unit, configured to acquire a perturbation quantity produced on a transmission link with a certain length and presented in form of the summation of weighted items, each item being a product of transmitting pulse information symbols at one or more moments relative to the current moment, and each item being weighted by a pre-obtained weighting coefficient corresponding to that item; characterized in that the nonlinear compensating apparatus further comprises: a perturbation quantity processing unit, configured to combine the items at the output of the perturbation quantity acquiring unit based on the weighting coefficients, so as to render a sum of combinations of addition and multiplication of symbols in a finite symbol set; and an information compensating unit, configured to calculate a difference between the symbol information sequence and the perturbation quantity at the output of the perturbation quantity processing unit to obtain a compensated symbol information sequence, so as to cause the transmitting side to transmit signals according to the compensated symbol information sequence, wherein the perturbation quantity processing unit is configured to combine the items to which the equal or approximately equal weighting coefficients correspond, or to combine the items to which the equal or approximately equal real parts of the weighting coefficients correspond, or to combine the items to which the equal or approximately equal imaginary parts of the weighting coefficients correspond, and wherein the perturbation quantity processing unit is configured to quantize the weighting coefficients before combining the items. a perturbation quantity processing unit, configured to combine the items at the output of the perturbation quantity acquiring unit based on the weighting coefficients, so as to render a sum of combinations of addition and multiplication of symbols in a finite symbol set; and an information compensating unit, configured to calculate a difference between the symbol information sequence and the perturbation quantity at the output of the perturbation quantity processing unit to obtain a compensated symbol information sequence, so as to cause the transmitting side to transmit signals according to the compensated symbol information sequence, wherein the perturbation quantity processing unit is configured to combine the items to which the equal or approximately equal weighting coefficients correspond, or to combine the items to which the equal or approximately equal real parts of the weighting coefficients correspond, or to combine the items to which the equal or approximately equal imaginary parts of the weighting coefficients correspond, and wherein the perturbation quantity processing unit is configured to quantize the weighting coefficients before combining the items.