The invention discloses a method for adjusting quantization quality in coding. The method comprises the following steps: two or more scaling factors are used for adjusting a first sampled value whichis used for coding. The adjusted first sampled value is then quantified to obtain a quantified sampled value. Scaling factor effects in the quantified sampled value are removed to obtain a second sampled value. The global gain is obtained through the first sampled value and the second sampled value. The information about the obtained quantified sampled value and the two or more scaling factors together with the global gain are exported as coding stream. The invention also discloses a method for adjusting quantization quality in decoding and a device for adjusting quantization quality in codingand decoding. The method and device disclosed in the invention greatly reduce the complexity and better adjust quantization quality in important parts to achieve better coding effects.