On the basis of analyzing the disadvantage of the existing keyboard circuit, a new kind of matrix keyboard circuit is proposed. The existing matrix keyboard circuit, reducing the amount of the I/O of microcomputer (MCU) for controlling with a variety of methods. However, detecting combination of buttons and identifying buttons for different pressed time can't get both at the same time. Combined with additional counter, decoder and a number of diode, the 4×4 matrix keyboard can be detected and identified only by two MCU I/O port. At the same time a structure for buttons detection is built in programming to record the information for the combination of buttons and time for the pressed button. The experimental results show that the improved matrix keyboard circuit can correctly identify a single key and combination, also recognizing buttons for different pressed time. In addition, it is conveniently transplanted to other processors for the simple control interface and programming.