The embodiment of the invention discloses a method and a device for optimizing the transmission performance. The method comprises the steps of adjusting adjustable parameters of each span, and determining adjustable parameters when a Q factor of a receiving terminal is the maximum, wherein the adjustable parameters comprise the incident power and the amplifier gain of each span; and determining the corresponding Q factor from the first span according to the incident power and the amplifier gain of each span, and using the amplifier gain corresponding to the Q factor to act as the adjustment amount of the corresponding span when the Q factor meets a preset condition.