A method for calculating a nonlinear transmission impairment of an optical fiber link, comprising: determining (S101a) that no pump light exists in an optical fiber link, obtaining a factor of intra-band nonlinear noise that is in the optical fiber link and does not pass through an optical filter, and obtaining integral power in signal light bandwidth of a span in the optical fiber link; correcting (S102a) the factor of intra-band nonlinear noise that does not pass through an optical filter, to obtain a factor of intra-band nonlinear noise of the span in the optical fiber link that passes through an optical filter; calculating (S103a) nonlinear noise of the span in the optical fiber link by using the following formula: P NL = α intra ( n)·( P S) 3; wherein, P NL represents the nonlinear noise power of the span; α intra (n) represents the factor of intra-band nonlinear noise of the span that passes through an optical filter; n represents the number of optical filters through which a signal light of the span passes; and P S represents the integral power in the signal light bandwidth of the span; and obtaining (S104a) total nonlinear noise of the optical fiber link according to the nonlinear noise of the span in the optical fiber link, and obtaining a nonlinear transmission impairment of the optical fiber link based on the total nonlinear noise of the optical fiber link. determining (S101a) that no pump light exists in an optical fiber link, obtaining a factor of intra-band nonlinear noise that is in the optical fiber link and does not pass through an optical filter, and obtaining integral power in signal light bandwidth of a span in the optical fiber link; correcting (S102a) the factor of intra-band nonlinear noise that does not pass through an optical filter, to obtain a factor of intra-band nonlinear noise of the span in the optical fiber link that passes through an optical filter; calculating (S103a) nonlinear noise of the span in the optical fiber link by using the following formula: P NL = α intra ( n)·( P S) 3; wherein, P NL represents the nonlinear noise power of the span; α intra (n) represents the factor of intra-band nonlinear noise of the span that passes through an optical filter; n represents the number of optical filters through which a signal light of the span passes; and P S represents the integral power in the signal light bandwidth of the span; and obtaining (S104a) total nonlinear noise of the optical fiber link according to the nonlinear noise of the span in the optical fiber link, and obtaining a nonlinear transmission impairment of the optical fiber link based on the total nonlinear noise of the optical fiber link. P NL = α intra ( n)·( P S) 3; wherein, P NL represents the nonlinear noise power of the span; α intra (n) represents the factor of intra-band nonlinear noise of the span that passes through an optical filter; n represents the number of optical filters through which a signal light of the span passes; and P S represents the integral power in the signal light bandwidth of the span; and obtaining (S104a) total nonlinear noise of the optical fiber link according to the nonlinear noise of the span in the optical fiber link, and obtaining a nonlinear transmission impairment of the optical fiber link based on the total nonlinear noise of the optical fiber link.