Abstract: To address the issue of rock burst disasters induced by the fracture of thick-hard roof strata, focuses on deep thick and hard roof. By integrating theoretical analysis, engineering experiments, and field monitoring, the fracture characteristics of thick-hard roofs under backfill mining conditions were investigated. A mechanical model for the settlement of thick-hard roofs based on thick plate theory was established, and the equation for the deflection curve of the thick-hard roof under mining-induced conditions was derived. The influence characteristics of the effective boundary size and filling rate of the filling body on the deformation of the roof were quantified, and the relationship between thick and hard roof and effective filling parameters was clarified. Based on this, a method for controlling the height of overburden failure was proposed using an equivalent mining height model. The spatial evolution characteristics of thick-hard roofs under backfill conditions were elucidated, and revealed the disaster reduction and erosion prevention mechanism of thick and hard roof in deep filling mining. Practical validation was conducted using a “dual synergy” backfill ratio enhancement technology. The results showed that after applying the “dual synergy” enhancement technology, the backfill ratio increased from 75% to 90%, and the proportion of underconnected roof in the total settlement of thick hardtop plates under four filling rates is 86%, 80%, 72%, and 55%, the effective boundary range expanded significantly, while the effective backfill space grew from 2.63 m to 3.25 m. This increased the contact area between the filling material and the thick and hard top plate, enhancing the load-bearing capacity of the backfill by approximately 55%. Meanwhile, with the increase of filling rate, the settlement of the roof in the effective boundary area decreased significantly, the settlement curve of thick and hard roof showed a downward trend as a whole, the settlement of the roof has decreased from 800 mm to 62 mm, the average energy and frequency of microseismic events decreased significantly. Through the improvement technology of enhancing the “dual collaboration” filling rate, the purpose of disaster reduction and erosion prevention has been achieved in the deep thick and hard roof working face. significantly mitigating rock burst risks and ensuring the safe mining of deep thick-hard roof conditions.