Abstract: In order to explore the difference between the in-situ and indoor strength of the filling body resulting from the flow and settlement of filling materials in the stope,the devices for stope filling with unclassified tailings were constructed on the basis of similar simulation theory,and simulation test of stop filling with unclassified tailings was carried out.After drilling sampling and strength measurements of the filling body of the similar stope,the paper compared and analyzed the strength from different layers and locations and the strength from indoor ratio test.The experimental results show that the strength of the unclassified tailings filling at different levels decreases with the flow direction of the filling slurry at first,then increases and again decreases.The attenuation rate of the filling body in 28 d compared with indoor test results is 28 %,and the strength enhancement rate was 63 %.With the feeding end as the starting point,the intensity attenuation region is in the first 7 %-28 % of the stope length and the intensity enhancement region is in the 42 %-84 % of the stope length.Except for the top layer,the average strength of the other filling bodies is higher than the indoor ratio strength by 19.7 %.