The invention relates to a highway tunnel middle sandwich rock partition wall stability evaluating method. According to the method, sensors distributed at two sides of a tunnel middle sandwich rock partition wall in a matrix form are used for performing micro-seismic monitoring; seismic wave information of a rock breaking seismic source and an auxiliary seismic source is separated out from the micro-seismic monitoring result; the crack position is primarily positioned according to the micro-seismic wave information on the basis of the position of micro-seismic waves generated in the rock breaking seismic source; the crack position is further and precisely positioned according to a wave velocity model after the optimization of seismic wave information of the auxiliary seismic source by a double-difference imaging positioning method; a micro-seismic event group generated by the crack in the set space at the set time is selected for performing clustering analysis to obtain the spatial and temporal distribution characteristics and the destructive evolution characteristics of the micro-seismic event; the quantitative description on the rock body rupture degree is performed on the basis of the characteristics; the evolution process of the rock body rupture degree is deduced; further, the stability of the middle sandwich rock partition wall is evaluated. The method has the advantages that the stability of the middle sandwich rock partition wall can be fast evaluated; the tunnel construction safety and the later-period normal operation are ensured.