In order to effectively improve the precision of the astronomical determination of space target

sub-pixel positioning technology research is very important for CCD exploration images. This article firstly systematic analysis of the main factors which affect the positioning accuracy

such as image noise

discrete sampling error and window selection etc.. Combining with the CCD imaging characteristics

a target centroid location method which based on energy accumulation is proposed. This method using interpolation technique to reduce the inconsistency which caused by the difference between the actual sensitive area light intensity and discrete sample points

and then by energy accumulation of diffuse plaque to adaptive selection the correct target window

by gray optimizing for the target to reducing random noise effect

finally using squared weighted centroid localization method to get the high precision position. Experimental results show that the method has strong anti-interference ability and stability

positioning accuracy can reach 0.01 pixels. It is suitable for low SNR condition.