A method and system are provided for reconstructing complete charge and discharge data based on partial charge and discharge data of a battery, in particular, a lithium battery. The method includes the following steps: A, acquiring the partial charge and discharge measured data curve, including a plurality of discrete sampling point data, of the battery; B, determining the initial point of the partial charge and discharge measured data curve relative to a preset global central reference data curve; C, determining an approximate curve by using the partial charge and discharge measured data curve and multiple preset sub-file central reference data curves according to linear reconstruction or least-square reconstruction, and according to the approximate curve and the initial point of the partial charge and discharge measured data curve relative to the preset global central reference data curve, supplementing the remaining charge and discharge measured data curve except the partial chargeand discharge measured data curve, thereby reconstructing a complete charge and discharge measured data curve. The method can reconstruct the complete charge and discharge measured data curve with high precision by using the partial charge and discharge measured data curve.