The invention relates to a coding method and a coding circuit for a matrix keyboard, and belongs to the field of keyboards of electric accessories. The coding method for the matrix keyboard is characterized in that: the matrix array of the keyboard has M rows and N columns; the input signal of the m-th row and n-th column key positioned on the matrix array is compiled as a code; and the code comprises position information representing the row and the column of the key and signal information. The coding circuit for realizing the coding method comprises the keyboard with the matrix array of M rows and N columns and is characterized in that: the keys of the keyboard are connected with the input end of the coding circuit respectively; and the output ends of the coding circuit are divided into a row output end, a column output end and other position output ends respectively and are connected with the input port of the keyboard controller respectively. The coding method can realize that few output lines can identify all the key signals. The coding circuit has high generality and wide application range and can be connected with the various conventional contact keys or electronic switches.