Abstract: In view of the lack of measured data of failure depth of miningfloor in deep buried and ultra-long working face, the stress, water pressure and strain sensing tests were carried out on the fault part of the second level deep ultra-long working face and the floor of intact coal seam in Chengjiao coal mine by using the field test method. Two measuring holes were arranged on the typical 21105 working face for disturbance and failure monitoring of floor respectively. A strain sensor, stress sensor and water pressure sensor were buried in the vertical depth of floor 10.5 ~ 11.5m in the fault part, and the monitoring points ranged from 65m before mining to 42m after mining. Four strain sensors and one stress sensor were buried in 18.0-32.0 m vertical depth of complete coal seam floor respectively, and the measured data of disturbance failure depth of mining floor were obtained from 55m before mining to 52m after mining. The experimental results show that the depth of mining disturbance is much greater than 10.5m, and the water pressure and additional stress increase first and then decrease gradually, indicating that the surrounding rock is affected by mining, but the influence is very small. In the vicinity of intact coal seam, the increment range of strain induction at measuring point 5 and 4 is 15779με and 12023με, respectively. The strain induction degree of measuring point 3 and 1 is relatively weak, and the normal working state is basically maintained during the whole observation process. The maximum value of additional stress at measuring point 2 is only 14 MPa. The failure depth of the working face floor ranges from 22.0 ~ 27.0m. The test data provide scientific basis for the design of water hazard control scheme for the deep buried and long working face of suburban coal mine.