A state detecting method applied to a mobile device includes: arranging a depth sensor at the bottom of the mobile device, obtaining a detection signal of the depth sensor, and determining if the mobile device is in a lifted state, a tilted state, or an edge-bordering state, based on the numerical value of the detection signal of the depth sensor. The lifted state is associated with the mobile device without contacting with a support surface. The tilted status is associated with one end of the mobile device contacting the support surface and the other end of the mobile device without contacting the support surface. The edge-bordering state is associated with the mobile device located at the edge of the support surface. Accordingly, when the mobile device is in any of the aforementioned states, an appropriate response can be implemented.