Abstract: In order to ensure unsupported roof distance of roadway driving with broken roof, one test method of unsupported roof distance determination was proposed by using a special support method on the tunnel roof to ensure the roadway roof on the free state in short time and small range. Observing the changes of surface deformation and roof separation in this short time, evaluating the roof stability, the reasonable unsupported roof distance is determined initially. Then combining with the haulage gate condition in 4103 working face in Jianxin Coal Mine, the study verifies the roof stability while driving the roadway on different unsupported roof distance with numerical simulation, finally determines the unsupported roof distance. The successful application Xinjian Coal Mine improves the speed of evaluation of the roadway.