A method for obtaining a performance parameter of an optical network link, comprising: acquiring actual optical power from each monitoring point of an optical network link by measuring; correspondingly acquiring theoretical optical power of each monitoring point calculated by using a theoretical model; performing modification on at least one parameter of an amplifier gain and a link loss of the optical network link in the theoretical model by using the actual optical power and the corresponding theoretical optical power of each monitoring point; and obtaining a performance parameter value of each node in the optical network link from the modified theoretical model; wherein the performing modification on at least one parameter of an amplifier gain and a link loss of the optical network link in the theoretical model by using the actual optical power and the corresponding theoretical optical power of each monitoring point comprises: subtracting corresponding theoretical single-wave output optical power calculated by using the theoretical model from actual single-wave output optical power of an erbium-doped fiber amplifier, EDFA, monitored by an optical performance monitor, OPM, to obtain a difference value between actual output optical power and theoretical output optical power of each single wave; comparing a difference value between actual optical power and theoretical optical power of each single wave with a preset threshold; in a case that at least one of difference values is greater than the threshold, modifying theoretical single-wave input optical power of the EDFA in the theoretical model; and using the modified theoretical single-wave input optical power of the EDFA to modify a link loss of a transmitting end of the optical network link in the theoretical model, wherein the link loss of a transmitting end is a link loss between a laser in the transmitting end and the EDFA. acquiring actual optical power from each monitoring point of an optical network link by measuring; correspondingly acquiring theoretical optical power of each monitoring point calculated by using a theoretical model; performing modification on at least one parameter of an amplifier gain and a link loss of the optical network link in the theoretical model by using the actual optical power and the corresponding theoretical optical power of each monitoring point; and obtaining a performance parameter value of each node in the optical network link from the modified theoretical model; subtracting corresponding theoretical single-wave output optical power calculated by using the theoretical model from actual single-wave output optical power of an erbium-doped fiber amplifier, EDFA, monitored by an optical performance monitor, OPM, to obtain a difference value between actual output optical power and theoretical output optical power of each single wave; comparing a difference value between actual optical power and theoretical optical power of each single wave with a preset threshold; in a case that at least one of difference values is greater than the threshold, modifying theoretical single-wave input optical power of the EDFA in the theoretical model; and using the modified theoretical single-wave input optical power of the EDFA to modify a link loss of a transmitting end of the optical network link in the theoretical model, wherein the link loss of a transmitting end is a link loss between a laser in the transmitting end and the EDFA.