The invention discloses a steep slope detecting sensing device. The device comprises a mounting frame, wherein a mounting cavity is arranged on the mounting frame, and a mounting base is arranged in the mounting cavity; a transmitting sensor and a receiving sensor are arranged on the mounting base, a partition part is arranged on the part, between the transmitting sensor and the receiving sensor,of the mounting base, the partition part partitions the mounting cavity into a transmitting region and a receiving region, and clearance openings are formed in the part, corresponding to the transmitting region and the receiving region, of the bottom of the mounting frame; and a signal angle reflecting plate is further arranged in the transmitting region, signals of the transmitting sensor are transmitted towards the surface of the signal angle reflecting plate, and the receiving sensor is sleeved with a receiving guide cover. According to the device, the anti-interference function is achieved; and in addition, the detection precision is guaranteed, and the usability is improved.