Abstract: Numerical simulation was conducted to gain greater insight into the flow structure of trapezoidal pin-fin duct and get detailed knowledge of the heat transfer on the endwall surface.The array geometries have short pin heights and small chord-wise pin spacing.Numerical results show that,the calculated flow resistances and chord-wise ejection mass flow rate agree well with the experimental data,and the heat transfer pattern is well simulated.The numerical results also show that the flow direction in pin-fin region is mainly chord-wise.There are a lower velocity and lower turbulence intensity region behind the cylinder.