Abstract：In order to prevent water inrush from fault motherboard,proper setting width for waterproof coal pillar on fault is necessary.Taking F29 fault with weak water conductivity as an example,old calculation methods and seting rules for fault waterproof coal pillars were used to calculate the setting width of F29 fault waterproof coal pillar.According to the formula and water inrush mechanism of faults,the unreasonableness of old calculation formula was discussed.The width of fault fracture band and width of yield band that reveal the factors of fault properties,fault size,and fault aquosity should be added.Base on the discussion,a new setting width of fault waterproof coal pillar was deduced,and the rationality was also demonstrated.

Keyword：waterproof coal pillar;setting width;width of fracture band;width of yield band;