A broadband cutting force measuring device comprises a knife shim in the front end of a knife handle, a triaxial vibration accelerometer is embedded into the knife shim, the front end of the knife handle is pasted with a Wheatstone measuring bridge formed by connecting resistance strain gauges, the output ends of the triaxial vibration accelerometer and the Wheatstone measuring bridge are connected to the input end of a cutting force signal preprocessing and collecting device, and the output end of the cutting force signal preprocessing and collecting device is connected with the input end of a host computer system. Thus, cutting force signals of low and high frequency bands can be measured accurately in the cutting process of a high-precision numerical control machine tool, and the measuring device has the advantages of high reliability and practicality.