A sensor assembly, comprising a connecting part used for connecting a base to be tested and a bearing part used for bearing, wherein the bearing part is connected to the connecting part, the bearing part comprises a first sensing unit and a second sensing unit, wherein the measuring range of the first sensing unit is greater than that of the second sensing unit, characterized in that the first sensing unit has a first initial gap b1 from the connecting part, and the second sensing unit has a second initial gap b2 from the connecting part, the first initial gap b1 is smaller than the second initial gap b2, so that corresponding initial gaps are eliminated when a load applied to the bearing part reaches different extents, and the sensor assembly comprises an elastic gasket (225, 241) arranged such that: when the acting force borne on the bearing part is lower than a preset value, the first initial gap b1 is not eliminated and the first sensing unit does not contact with the connecting part and the second sensing unit contacts with the connecting part via the elastic gasket (225, 241), and when the acting force borne on the bearing part reaches a predetermined value higher than the preset value, the first initial gap b1 is eliminated and the second sensing unit contacts with the connecting part via the elastic gasket (225, 241), wherein the first sensing unit has a columnar sensing structure and comprises a columnar body, and the first sensing unit contacts with the connecting part via the columnar body when said acting force reaches the predetermined value, wherein at that point, the first sensing unit and the second sensing unit bear the load jointly, or wherein the bearing part comprises a cylindrical body corresponding to a central portion of the connecting part and a peripheral portion corresponding to a peripheral portion of the connecting part, the cylindrical body and the peripheral portion being formed integrally, wherein the first sensing unit contacts with the connecting part via the cylindrical body when said acting force reaches the predetermined value and the load is borne on the cylindrical body and the peripheral portion that are formed integrally. when the acting force borne on the bearing part is lower than a preset value, the first initial gap b1 is not eliminated and the first sensing unit does not contact with the connecting part and the second sensing unit contacts with the connecting part via the elastic gasket (225, 241), and when the acting force borne on the bearing part reaches a predetermined value higher than the preset value, the first initial gap b1 is eliminated and the second sensing unit contacts with the connecting part via the elastic gasket (225, 241), wherein the first sensing unit has a columnar sensing structure and comprises a columnar body, and the first sensing unit contacts with the connecting part via the columnar body when said acting force reaches the predetermined value, wherein at that point, the first sensing unit and the second sensing unit bear the load jointly, or wherein the bearing part comprises a cylindrical body corresponding to a central portion of the connecting part and a peripheral portion corresponding to a peripheral portion of the connecting part, the cylindrical body and the peripheral portion being formed integrally, wherein the first sensing unit contacts with the connecting part via the cylindrical body when said acting force reaches the predetermined value and the load is borne on the cylindrical body and the peripheral portion that are formed integrally.