1. A feature point matching method of a planar array of a four-camera group, comprising steps as follows: a1. taking any imaging plane of four imaging planes corresponding to four cameras of a four-camera group as a base imaging plane, and determining, for one feature point on the base imaging plane, all matching points matching the feature point on an imaging plane adjacent to the base imaging plane in a lateral direction; a2. for the feature point on the base imaging plane in the step a1, finding out all matching points matching the feature point on an imaging plane adjacent to the base imaging plane in a longitudinal direction; a3. re-matching all of the matching points determined in the step a1 and all of the matching points found out in the step a2, to determine corresponding sub-matching point groups; a4. according to the feature point on the base imaging plane and all of the sub-matching point groups determined in the step a3, identifying matching points on an imaging plane at a diagonal position corresponding to the feature point on the base imaging plane and all of the sub-matching point groups determined in the step a3, wherein the imaging plane at the diagonal position is an imaging plane located at the diagonal position of the base imaging plane; and a5. according to the feature point on the base imaging plane, all of the sub-matching point groups determined in the step a3 and the matching point identified in the step a4, determining unique matching point groups on the four imaging planes corresponding to a same viewed point.