The invention provides a compound for targeted ubiquitinated degradation of Smad3. The compound for targeted ubiquitinated degradation of Smad3 is formed by connecting a compound shown in a formula (I) and an ubiquitin ligase E3 identifying ligand shown in a formula (II) through a Linker shown in a formula (III) for connecting the two. The invention constructs a compound which can be specifically combined with Smad3 to degrade Smad3 proteins in a targeted manner through ubiquitination by jointly applying computer virtual screening and a technology of target ubiquitinated degradation of proteins, and the compound is verified to be capable of degrading Smad3 in a targeted ubiquitinated manner. As Smad3 is the major known fibrosis-inducing signaling protein, the Protac theoretically has an anti-fibrosis effect. Moreover, the molecular weight of the compound is small, so that the Protac can get into or out of cells freely, and therefore, the compound is likely to become a novel drug for treating fibrosis. The compound not only has scientific value, but also has important social value.