Abstract: According to the large cross section open-off cut,deep depth, broken roof support difficulty of the fully mechanized high cutting coal mining face in Zhaog u No.2 Mine,a combined support system with bolt/steel mesh/anchor plus shield canopy was provided for the large cross section open-off cut in the mine.With the analy sis on the roof lithology of the open-off cut,the bolt(anchor)support theory and mechanism was applied to the design on the support parameters of the secondary reamin g of the large cross section open-off cut.The 020x4 000 mm type thread steel bolt and the 021.6x12 000 mm type steel strand anchor were applied to the roof reinforce ment after the secondary remaining of the open-off cut.the site mine strata pressure monitoring and measuring results showed that the optimized support structure coul d effectively control the deformation of the roof and the two sidewall of the large span and high open-off cut under the complicated conditions and the support effect was good.