Abstract: In order to seek the causes of imbalance of sublevel caving hydraulic support, top coal caving at the end face and coal rib spalling, and to evaluate the adaptability of hydraulic support, we investigated the situation of surrounding rock in stope and working status of hydraulic support with the method of field measurement. After that, the force condition of support was calculated and the bearing characters were analyzed by mechanical calculation. The results show that the reasons for the instability of hydraulic support are as follows. The face-to-canopy distance caused by the large cutting height is so big that the hydraulic support cannot support the roof in time, so top coal broke and caved seriously, and then cavities generated on the top beam, which resulted in low holding power and skew hydraulic support. The rated resistance of supports used in the test point is sufficient, but the rated thrust force of hoisting jack in front beam is only 1 060 kN and deficient to meet the required value of 1 139 kN. Therefore, the hydraulic support cannot adapt the production condition of the working face completely. Finally, reasonable suggestions and measures were proposed to these issues.