The invention relates to coding techniques and discloses a gain quantitative method and a device. The gain quantitative method includes the steps of: calculating the fixed code book gain of a sub-frame of a frame signal; quantizing the fixed code book gain and obtaining a quantized value of the fixed code book gain of the sub-frame; using the quantized value of the fixed code book gain and the fixed code book gains of other sub-frames of a signal to calculate predictive coefficients of the fixed code book gains of other sub-frames; and quantizing the predictive coefficients of the fixed code book gains of other sub-frames. By the use of the technical proposal provided by the embodiment of the invention, an estimation energy value is not necessarily quantized, thus saving bits of quantization.