The invention discloses cyclic diketopyrrolopyrrole conjugated compounds as well as a preparation method and an application thereof. The structural formula of the compounds are shown as formula I in the description, wherein in the formula I, each of R1 and R2 is one independently selected from hydrogen, C1-C50 straight-chain or branch-chain alkyl, C1-C50 straight-chain or branch-chain alkyl containing amido bonds, ether bonds and ester bonds and C1-C50 straight-chain or branch-chain perfluoroalkyl; each of R3 and R4 is one independently selected from substituted or non-substituted phenyl, thienyl, thiazolyl, pyridyl, quinolyl, furyl, pyrryl, imidazolyl, naphthyl and pyrenyl or a combined fragment of the groups linked by single bond, double bonds, triple bonds, oxygen, sulfur or nitrogen; nis an integer of 2-20. The synthesis steps are short, the conditions are mild, and the operation is simple; raw materials are convenient and easily available, and industrial production is easy; the compounds have good chemical stability, highly absorb visible light and are beneficial to inhibition of molecular aggregation, and a 3D charge transport channel is formed.