A framework structure of information feedback device of a piano learning machine. A row of sensor windows are arranged on a bottom surface of a shell profile and a circuit board insert slot is arranged in a hollow chamber of the shell profile. Each of the two ends of the shell profile is provided with an end cover. An adjusting device is disposed on an external side of each end cover and includes a base block and a height adjusting block. The framework structure is advantage in that the height adjusting block can rotate and be locked tightly onto the end covers and allows rotating adjustment with transversal direction being an axis so that an applicable scope of the device is greatly improved. The adjusting device is simple in structure and is convenient to use. A plurality of height adjusting holes or long holes are added on the end covers so that the height adjusting block can be locked in any position in the different height adjusting holes or long holes, thereby allowing a large-range height adjustment. A surface mounting slot is designed in an oblique manner so that observation by a user is convenient from a front side obliquely. A retractable light guide groove and a light insulation block are employed in the sensor mounting windows so that a vertical interference of environmental light noise and interference of infrared ray of the user can be eliminated. Stability of a signal is improved.