In order to research the spatial characteristics of human vision system, the luminance and chromatic contrast sensitivity function (CSF) is measured for sinusoid wave patterns on a CRT displayer using the psychophysical method of interleaved staircase. Based on the CIELAB space, the contrast is defined as the ratio between color difference ΔE*ab and the average luminance L*, so that the luminance and chromatic CSF can be compared in the uniform scale. The luminance and chromatic CSF for the sinusoid wave patterns whose average color is neutral gray (L*=76，a*=b*=0) are measured under three field sizes of 10°, 6° and 2.44°, respectively, for spatial frequencies from 0.5 to 23.4 cycle /(°). The test data are fitted using different exponent functions. It is found that the peak luminance CSF values and the cross points of chromatic CSF curves of different color directions change with the field sizes. The ratio curves between the luminance CSF and the chromatic CSF under different fields are also obtained, which reflect the difference of human′s sensitivity to the luminance and chromatic contrast.