This　paper　developed　and　validated　a　quasi-dimensional　model　for　predicting　the　combustion　performance　in　hybrid　hydrogen　gasoline　engines.　In　this　model,　the　two-zone　thermodynamic　differential　equations　were　established　base　on　the　ideal　gas　equations　and　conservation　equations　of　mass　and　energy　for　the　burnt　and　unburned　zones,　respectively.　The　heat　release　rate　was　determined　by　the　fractal-based　turbulence　entrainment　model.　The　laminar　flame　speed　correlation　of　hydrogen-gasoline　blends　was　implemented　in　the　turbulence　entrainment　model　to　characterize　the　variation　of　combustion　properties　after　hydrogen　addition.　The　numerical　analysis　code　MATLAB　was　applied　to　solve　the　differential　equations.　The　predicting　accuracy　of　the　proposed　model　was　evaluated　through　the　comparison　with　experimental　results　under　different　hydrogen　volume　fractions,　equivalence　ratios,　and　manifolds　absolute　pressures.　The　comparison　results　confirmed　that　the　proposed　model　could　capture　the　combustion　behavior　for　various　operating　conditions,　suggesting　that　this　model　is　applicable　for　combustion　performance　prediction　of　hybrid　hydrogen　gasoline　engines.　Copyright　©　(2014)　by　the　Committee　of　WHEC2014　All　rights　reserved.