Phase unwrapping is a very difficult problem because of the existence of many unpredictable factors. In order to acquire the more accuracy phase unwrapping,a detailed analysis about the several classic quality weighting factors is given. First,the full mathematical formula of them are provided,then the principle of derivation is described and the characteristics of them are analyzed. According to their physical meaning,some improved algorithms in the same field or related fields are proposed. The experiments prove the feasibility and superiority of improved algorithms. It is also testified that the analysis has universal guiding significance for understanding and studying phase unwrapping.