Along with the rising demands of product fineness, fine-powder grinding technology is widely applied. The conveying facility of such equipment is ultrafine vertical mill. However, the capacity of ultrafine vertical mill sometimes can be much lower than designed. According to operating experiences, we summerize some reasons and solutions.1.Insufficient bucket loading Loading quantity directly influence the capacity of ultrafine vertical mill. There are 3 reasons effecting bucket loading: material surface height, main wheel speed and material status. To ensure full loaded bucket, low speed wheel, higher feeding port and reasonable bucket shape are needed.2.Material leaking If the material quantity of upper bucket is obviously lower than lower bucket, there is to be a leaking problem. The problem is caused by loose belt. Material leak out for bucket or equipment vibration. Increase belt tension, ensure a balanced operation, and lower the vibration, all these will solve the problem.