The invention relates to a field of combination and output of two different signals and specifically relates to a device and method used for signal combination of a self diagnosis sensor and a commonsensor. The device includes a high speed optical coupler, a single-chip microprocessor and an output drive circuit. The high speed optical couple is used for collecting electric level states of self diagnosis sensor signals and common sensor signals. The single-chip microprocessor detects the stage of input signals through inner programs intelligently and performs OR operation, and performs maintaining or negation on the signals through combining the operation result with the self diagnosis sensor signal state and outputs a detection result to an output drive circuit. The output drive circuitis used for amplifying control signals sent by the single-chip microprocessor and enhancing the drive capability of the output signals. The device provided by the invention can recognize external input signals intelligently and then performs AND/OR union operation on the external input signals, and outputs control signals with diagnosis pulses according to electric level state of an input channel.