Abstract: The residual deformation of foundation in an abandoned goaf threatens the safety operation of the proposed project， and the foundation stability evaluation is required before its development and utilization. However， the current foundation stability evaluation index system is complicated，which can easily lead to unscientific and unreasonable evaluation results. In view of this， this paper takes the Wuyun expressway construction as an example，which is located above the abandoned goaf of Guhanshan Mine and Wucun Mine in Henan Province.First of all，according to the four principles of uniqueness，purpose，feasibility and observability， qualitative screening is conducted.Secondly，screened quantitatively is conducted based on the theory of improved grey relational degree，and then a minimalist stability evaluation system suitable for Wuyun expressway construction foundation is established.The effectiveness and reliability of established minimalist stability evaluation system is analyzed by using the validity coefficient and correlation coefficient.Wuyun expressway construction foundation is convicted in a basically stable state by using the proposed minimalist stability evaluation system，and the evaluation result is consistent with those of other evaluation index systems，confirming its accuracy. Because the minimalist stability evaluation system only contains three main indicators，it can greatly reduce the calculation burden of the system and simplify the evaluation process.

Key words: Abandoned goaf, Foundation stability, Indexes screening, Improved grey relational degree algorithm