Abstract: The flow characteristics in aluminum shape extrusion with the flow-guide die added are analyzed by both the simulating experiment method and the theoretical method．The theoretical basis for minimum height of flow-guide die cavity is provided．The flow line equation，the kinematically admissible velocity field ，the strain rate field and the deformation power of solid aluminum shape with thin wall extrusion are obtained by the upper bound method based on the flow function ． The effects of the parameters ，such as deformation ratio，on minimum height of flow-guide die cavity are discussed．The minimum height when aluminum shape with thin wall is extruded can be expressed by 0.7～0.8 b0，where b0 is the half-width of the entrance of the flow-quide die cavity．The theoretical result is confirmed by experiment．The useful knowledeges for die design can be obtained．

Key words: Flow function method, Extrusion Simulating experiment, Aluminum shape, Flow-guide die