To address the issues of high unit consumption of flocculant and unstable underflow concentration in thetreatment of ungraded tailings at the Jiaojia Gold Mine, a series of static flocculation-settling tests, dynamic thickeningtests, and semi⁃industrial deep⁃cone thickening tests were conducted to systematically investigate the influencingfactors and optimize the flocculation-thickening process. Results show that in static tests, the anionic flocculant K739produced optimal settling performance at a pulp concentration of 12 % and a dosage of 15 g/t, significantly improvingunderflow concentration. However, overdosing led to loose floc structures and increased settling resistance. In dynamictests, when the treatment rate was 0.6 t/（m²·h）, the underflow concentration reached 67.66 %, with the overflow solidcontent below 200×10⁻⁶. Prolonging the compression time further improved the underflow concentration. Semi⁃industrialtests confirmed a negative correlation between treatment rate and underflow concentration. Considering the requirementthat overflow solid content should not exceed 200×10⁻ ⁶ , a recommended thickener throughput of 0.7 t/（m²·h）wasproposed. By optimizing slurry concentration, flocculant dosage, and treatment rate, and by increasing thickener heightto extend compression time, stable underflow concentrations above 72 % can be achieved. This provides both theoreticaland technical support for paste backfilling and resource⁃based utilization of mine tailings.