According to the poor reliability of fixture used in large inclined angle borehole and low strength of locking coupling in underground coal mine. By means of mechanical model, optimization calculation and finite element method, the relationship between the length of claw, opening angle and borehole diameter, component force of wedging in borehole wall is studied. The stress distribution of locking coupling, pin hole of claw is analyzed when screen pipe is cased. The results showed that the hang performance is better when the length of claw is 97 mm. The groove tip and pin hole of claw is the area of stress concentration, they will reach the yield limit consecutively.