The invention relates to a design and preparation method for a flexible force sensing element based on a continuous three-dimensional graphene or carbon nanotube field effect structure. Field effect conductivity changes under constant grid voltage of graphene or carbon nanotubes covering the surface of an elastomer pyramid strip are used by the sensing element, a grid electrode is design to be a plane flexible electrode covering the graphene or the carbon nanotube pyramid strip or the top end of an array, the area of a source leakage channel is increased under the compressive deformation for a pyramid by the grid electrode, the field effect conductivity is increased, and the element is high in deformation or loading flexibility. By the designation of the width of the strip, the density of the array and the elasticity modulus of base elastomer materials, force sensing elements with different flexibilities in the loading measurement range of 0-3 MPa can be obtained, and a force sensing film of which the transparency is higher than 80% and the bending curvature is less than 3 mm can be designed and prepared.