Based on foil RAE 2822, in order to research the effect of y+ of non-dimensional quantity parameters on computing precision of pneumatic parameters of foil, the computational grids created by ANSYS ICEM and the disperse format of N-S control equations with the method of finite volume method are employed, SST turbulence model is selected, pneumatic parameters of foil are numerically simulated. The relative error is analyzed, and the contour of pressure coefficient is drawn recurring to ANSYS CFX module under different y+. The results show that too large y+ leads to the increase of error, the computing precision is less change nearby the theoretic value 11.63 of y+ and lesser y+ may make the precision further improved, but higher precision couldn't be with too small y+. The impacts of y+ on the computing precision are various in different regions of foil boundary, and y+ selected between 2 to 4 is recommended when pneumatic parameters of foil are simulated.