A method for processing a lost frame, comprising: determining a synthesized high frequency band signal of a current lost frame; determining recovery information that corresponds to the current lost frame, wherein the recovery information comprises at least one of the following: a coding mode before frame loss, a frame class of a last frame received before the frame loss, and a quantity of continuously lost frames, wherein the quantity of continuously lost frames is a quantity of frames that are continuously lost ending with the current lost frame; determining a global gain gradient of the current lost frame according to the recovery information; determining a global gain of the current lost frame according to the global gain gradient and a global gain of each frame in previous M frames of the current lost frame, wherein M is a positive integer, wherein the global gain gradient is a weighting factor; and adjusting the synthesized high frequency band signal of the current lost frame according to the global gain of the current lost frame and a subframe gain of the current lost frame, to obtain a high frequency band signal of the current lost frame; the method further comprising: determining a subframe gain gradient of the current lost frame according to the recovery information; and determining the subframe gain of the current lost frame according to the subframe gain gradient and a subframe gain of each frame in previous N frames of the current lost frame, wherein N is a positive integer, wherein the subframe gain gradient is a weighting factor. determining a synthesized high frequency band signal of a current lost frame; determining recovery information that corresponds to the current lost frame, wherein the recovery information comprises at least one of the following: a coding mode before frame loss, a frame class of a last frame received before the frame loss, and a quantity of continuously lost frames, wherein the quantity of continuously lost frames is a quantity of frames that are continuously lost ending with the current lost frame; determining a global gain gradient of the current lost frame according to the recovery information; determining a global gain of the current lost frame according to the global gain gradient and a global gain of each frame in previous M frames of the current lost frame, wherein M is a positive integer, wherein the global gain gradient is a weighting factor; and adjusting the synthesized high frequency band signal of the current lost frame according to the global gain of the current lost frame and a subframe gain of the current lost frame, to obtain a high frequency band signal of the current lost frame; the method further comprising: determining a subframe gain gradient of the current lost frame according to the recovery information; and determining the subframe gain of the current lost frame according to the subframe gain gradient and a subframe gain of each frame in previous N frames of the current lost frame, wherein N is a positive integer, wherein the subframe gain gradient is a weighting factor. determining a subframe gain gradient of the current lost frame according to the recovery information; and determining the subframe gain of the current lost frame according to the subframe gain gradient and a subframe gain of each frame in previous N frames of the current lost frame, wherein N is a positive integer, wherein the subframe gain gradient is a weighting factor.