The　three-dimensional　k-Ε　model　for　turbulence　flow　was　used　to　investigate　the　flow　at　90　open-channel　junction,　and　the　hyperbolic　tangent　stretching　function　was　adopted　to　regenerate　the　mesh　for　obtaining　the　free　surface　elevation.　The　validity　of　the　model　was　verified　by　experimental　data.　The　main　characteristics,　such　as　the　variation　of　free-surface　elevation　and　the　secondary　current,　were　obtained　successfully.　Then,　the　effects　of　discharge　ratio　on　the　shape　indexes,　the　cross-section　mean　flow　angles　and　the　contraction　coefficients　were　analyzed.　The　results　well　agree　with　the　results　given　by　previous　researchers.