A method for constructing a sequencing template based on images from a single-molecule sequencing platform, wherein the images comprise first images, second images, third images and fourth images of the same field of view respectively corresponding to base extensions of four types of bases A, T, G, C or A, U, G, C; a plurality of nucleic acid molecules with optically detectable labels are present in the field of view during the base extension, and at least part of the nucleic acid molecules are present as spots on the images; sequential or simultaneous completion of the base extensions of the four types of bases once is defined as one cycle of sequencing; the first images comprise an image M1 and an image M2, the second images comprise an image N1 and an image N2, the third images comprise an image P1 and an image P2, and the fourth images comprise an image Q1 and an image Q2; the images M1 and M2 respectively come from two cycles of sequencing, the images N1 and N2 respectively come from two cycles of sequencing, the images P1 and P2 respectively come from two cycles of sequencing, and the images Q1 and Q2 respectively come from two cycles of sequencing; and the method comprises: combining any two of the images M1, M2, N1, N2, P1, P2, Q1 and Q2 in pairs for spot matching, such that the images M1, M2, N1, N2, P1, P2, Q1 and Q2 each participate in at least one combination to give a plurality of combination images each comprising a first overlap spot, with two or more spots distanced by less than a first predetermined pixel distance on a combination image being defined as a first overlap spot; and merging the first overlap spots on the plurality of combination images to give a spot set corresponding to the sequencing template. a plurality of nucleic acid molecules with optically detectable labels are present in the field of view during the base extension, and at least part of the nucleic acid molecules are present as spots on the images; sequential or simultaneous completion of the base extensions of the four types of bases once is defined as one cycle of sequencing; the first images comprise an image M1 and an image M2, the second images comprise an image N1 and an image N2, the third images comprise an image P1 and an image P2, and the fourth images comprise an image Q1 and an image Q2; the images M1 and M2 respectively come from two cycles of sequencing, the images N1 and N2 respectively come from two cycles of sequencing, the images P1 and P2 respectively come from two cycles of sequencing, and the images Q1 and Q2 respectively come from two cycles of sequencing; and the method comprises: combining any two of the images M1, M2, N1, N2, P1, P2, Q1 and Q2 in pairs for spot matching, such that the images M1, M2, N1, N2, P1, P2, Q1 and Q2 each participate in at least one combination to give a plurality of combination images each comprising a first overlap spot, with two or more spots distanced by less than a first predetermined pixel distance on a combination image being defined as a first overlap spot; and merging the first overlap spots on the plurality of combination images to give a spot set corresponding to the sequencing template. combining any two of the images M1, M2, N1, N2, P1, P2, Q1 and Q2 in pairs for spot matching, such that the images M1, M2, N1, N2, P1, P2, Q1 and Q2 each participate in at least one combination to give a plurality of combination images each comprising a first overlap spot, with two or more spots distanced by less than a first predetermined pixel distance on a combination image being defined as a first overlap spot; and merging the first overlap spots on the plurality of combination images to give a spot set corresponding to the sequencing template.