The invention discloses a handheld biomass measuring device, which comprises a horizontal push rod, a pressure sensor, a vertical connecting rod, a crossbeam, an acquisition module and two suspension straps. The pressure sensor is arranged between the horizontal push rod and the vertical connecting rod and used for acquiring the strength of resilience force when a crop deforms; the tail end of the crossbeam is connected with the upper end of the vertical connecting rod so that a user can hold the handheld biomass measuring device with a hand; one of the two suspension straps is hung on the neck of the user, and the other suspension strap is tied in the waist of the user, so that the horizontal push rod is kept horizontally; and the acquisition module is placed on the crossbeam and connected with the pressure sensor, a crop biomass prediction model is embedded into the acquisition module, and biomass is measured according to voltage signals of the crop resilience force acquired by the pressure sensor. The handheld biomass measuring device has the advantages of portability, quick measurement, zero damage and the like, and is particularly applicable to detecting biomass of small and medium groups of crops in small land parcels during field breeding, and measurement results are accurate and reliable.