Abstract: Near-infrared star detection system used three detectors to detect stars at the same time, analysed the relation between contrast and the detection parameters of near-infrared band during daytime, what's more, compared the contrast of different detectors, the result showed that: with the observer zenith angle increased, the star-background contrast increased linearly; when the solar zenith angle was greater than the observer zenith angle, the contrast similar to the exponential growth; out of a certain height, the contrast exponentially increased with the height increased; with the increased of the detection azimuth, contrast approximation Gaussian distribution; at the same time, background radiation contrast of different fields got minimum when the main field is 0; star-background contrast nearly symmetrical distribution with the alter of main field's detection azimuth, provide a better basis for the magnitude amendment.