The invention discloses a matrix keyboard scanning circuit and coding circuit. The matrix keyboard scanning circuit and coding circuit comprises a matrix keyboard, a first shift register, a second shift register, a status code register and a coder; the scanning method of the scanning circuit comprises following steps of converting the single-key operations, combined key operations or maintained statuses of the matrix keyboard into valid status codes and invalid status codes with the same binary length through control of a scanning pulse, a first shift pulse and a second shift pulse which satisfy a specific time sequence demand; outputting a valid key number corresponding to each valid status code or outputting invalid key numbers corresponding to all invalid status codes after the codes are coded by the coder, wherein different single-key operations, combined key operations or maintained statuses are only reflected in the differences of the status codes; and if key operation functions need to be reduced or increased, or if the key operation functions need to be adjusted, the structure of the keyboard scanning circuit does not need to be modified, and only the coder needs to be modified according to the corresponding relationships between the increased or reduced status codes and the key numbers. According to the circuits disclosed by the invention, it is unnecessary to compile and operate programs; and the work is reliable.