Circular　RNAs　(circRNAs)　are　a　class　of　highly　stable　and　closed-loop　noncoding　RNA　that　are　involved　in　the　occurrence　and　development　of　hepatocellular　carcinoma　(HCC).　However,　little　is　known　about　the　therapeutic　role　of　circRNAs　in　HCC.　We　found　that　high　circ_0058051　expression　was　negatively　correlated　with　the　prognosis　of　HCC　patients.　Circ_0058051　knockdown　attenuated　the　proliferation　and　colony　formation,　meanwhile　inhibited　migration　of　HCC　cells.　Circ_0058051　may　be　used　as　a　target　for　HCC　gene　therapy.　We　synthesized　a　novel　small　interfering　RNA　(siRNA)　delivery　system,　PEG-PCL-PEI-C14-SPIONs　(PPPCSs),　based　on　superparamagnetic　iron　oxide　nanoparticles　(SPIONs).　PPPCSs　protected　the　siRNA　of　circ_0058051　from　degradation　in　serum　and　effectively　delivered　siRNA　into　SMMC-7721　cells.　Meanwhile,　intravenous　injection　of　the　PPPCSs/siRNA　complex　could　inhibit　tumor　growth　in　the　subcutaneous　tumor　model.　In　addition,　the　nanocomposite　is　not　toxic　to　the　organs　of　nude　mice.　The　above　results　show　that　PPPCSs/si-circ_0058051　complex　may　provide　a　novel　and　promising　method　of　HCC　treatment.