The aerodynamic characteristics and confluent boundary layer of NHLP2D air foil are studied within the Reynolds number range from 1×106 to 30×106 and Mach number 0.197 by numerical simulation. Mesh scheme in the confluent boundary layer is carefully developed in the numerical model. Comparison with the existing test data and numerical data shows the model of present study is reliable. 〖JP3〗The Reynolds number effect on aerodynamic coefficient is obviously decreased when Re is larger than 1.5×107. And areodynamic coefficient shows a linear variation with Reynolds number for small angle of attack. As increasing Reynolds number, the thickness of confluent boudary layer decreases, and the wake intensity of slat and main element decreases. The width of wake also decreases as increasing Reynolds number. The slat wake remains strong at the trailing edge of flap at high Reynolds number which implies the interaction between wake and boundary layer decreases with the increasement of Reynolds number. The present study provides foundation for the subsequent research on the effect of Reynolds number on the slot flow.