Based on the low output and short working face before integration in Luning Mine, how to long the working face and conduct recovery mining was studied by theory analysis and numerical simulation, the length of the working face was added to 240 m, adopting the existed ZZ7500/22/45 support, the reasonable small coal column is 4.5 m, 4.5 ~ 6 m in practice, which reduced the coal column loss comparing to the original 15 ~ 30 m leaving coal pillar.