The　contraction　ratio　of　lower　bucket　is　an　important　parameter　of　the　series　jet　characteristics　of　the　allotypic　hybridtype　flip　bucket　(AHFB).　Due　to　the　effect　of　contraction　in　lower　bucket　and　diffused　in　upper　bucket,　the　jet　flows　cross　and　impact　in　the　space　domain.　Systematic　hydraulic　model　tests　were　developed　to　describe　the　rule　of　water-diversion　and　pressure　distributions.　This　paper　presents　the　variation　of　jet　trajectory　length　and　the　local　scour　of　this　combined　bucket.　Based　on　these,　the　variation　laws　and　estimation　equations　for　hydraulic　characteristics　with　different　contraction　ratio　are　proposed.　©　(2014)　Trans　Tech　Publications,　Switzerland.