In China's civil litigation, self-commissioned appraisal opinions are widely used as evidence. However, the theoretical community has not reached a consensus on the categorization of their evidence type, and there are contradictions in practice between strict proof and ambiguous legality, as well as conflicts between strong probative force and weak review rules. Re-examining from a normative perspective reveals that they do not fully meet the normative requirements of statutory expert opinions under China's Civil Procedure Law, nor do they fall under the category of illegal evidence subject to exclusion. Considering the essential factors that contribute to the probative effectiveness of self-commissioned appraisal opinions, this paper argues that they should be classified as defective appraisal opinions and proposes the construction of a corresponding rule system for the review and determination of defective appraisal opinion. At the pre-trial conference stage, the commissioning party should fulfill the obligation of evidence disclosure by proactively disclosing the self-commissioned appraisal opinions and appraisal materials. At the level of evidence admissibility, the non-commissioning party has the right to raise evidentiary objections against substantive factors affecting the admissibility of self-commissioned appraisal opinions, and judges should deny their admissibility when reasonable doubts arise. At the level of probative force, since the defects in the neutral procedural value of self-commissioned appraisal opinions cannot be rectified, they should be categorized as evidence requiring corroboration. Although they cannot independently establish case facts, their probative force can be enhanced through other corroborative evidence.