The invention relates to the technical field of harvesting machine detection, in particular to an engine and clutch differential speed detecting alarming device for a harvesting machine. The engine and clutch differential speed detecting alarming device comprises a first speed sensor used for detecting the rotation speed of a flywheel of an engine and a second speed sensor used for detecting the rotation speed of a clutch, and further comprises a controller used for processing and analyzing the difference between the two rotation speeds and conducting displaying alarming. The controller comprises a power assembly, a signal processing module, an MCU module, a rotation speed displaying module and an acousto-optic alarming module. The first speed sensor is electrically connected with the MCU module through the signal processing module, the second speed sensor is also electrically connected with the MCU module through the signal processing module, and the MCU module is electrically connected with the corresponding rotation speed displaying module and the corresponding acousto-optic alarming module respectively. The engine and clutch differential speed detecting alarming device for the harvesting machine has the advantages of being automatic in detection, convenient to maintain and adjust, convenient to operate and reasonable in design.