Abstract: The unsteady flow fields in baffled stirred vessel were simulated by unstructured tetrahedral mesh and sliding grid technique.On basis of comparisons of calculated mean velocity at blade tip and power number with experimental data,the influences of various different factors on the precision of numerical results are assessed quantitatively,and the key points about mesh generation and parameter settings that should be followed during modeling are pointed out.This paper provides theoretical evidences for unstructured tetrahedral mesh to be applied in CFD(Coputational fluid dynamics) analysis of baffled stirred vessels,and thus lay the essential research foundation of CFD design of novel impeller with elaborate shapes.