Abstract: The Zernike modal wavefront reconstruction error of Hartmann sensor on measuring the atmospheric disturbed wavefront analyzed in this paper. It’s shown that the wavefront reconstruction error is concerned with sub-aperture configuration type and the total Zernike mode number used in wavefront reconstruction algorithm. Experiential formulas to calculate the wavefront reconstruction error of a Hartmann sensor in Kolmogorov turbulence are also deduced. The experimenal data are analyzed and compared between two Hartmann sensors with 8x8 and 32x32 sub-apertures configuration respectively.