The high viscosity of heavy oil primarily stems from the aggregation of asphaltene molecules. Currently, surfactants are widely used as viscosity reducers to effectively lower the viscosity of heavy oil. This study employed molecular dynamics simulations and quantum chemical calculations to investigate the interactions between viscosity reducers⁃10 （OP⁃10）and sodium laurate (SL) with asphaltenes at different concentrations. The results show that when the molecular number of OP⁃10 (N(OP⁃10))=120 and the molecular number of SL (N(SL))=400, the composite viscosity reducer OP⁃10/SL can form micellar structures with asphaltenes. Meanwhile,the total number of hydrogen bonds in the system increases significantly from approximately 1 000 at N(OP⁃10)=30 and N(SL)=100 to about 3 800, forming a stable three dimensional hydrogen bond network. Based on visual analysis of simulation snapshots, statistics of hydrogen bond quantities and electrostatic potential distribution analysis, the viscosity reduction mechanism of this composite viscosity reducer is revealed, which provides a theoretical basis for the design and application of composite viscosity reducer systems represented by OP⁃10/SL.