Abstract: In the present,the relationship between the resolution of theoretical minimum angle and the accuracy of angle measurement were not gived,the scanning interval constraint conditions which is used to obtain the angular resolution that equal to the scanning interval and spot diameter size is also presented.To resolve these problems,the relationship between the conditions of the angular resolution equal to the scanning interval and spot diameter size and quantification accuracy and the relationship between the resolution of theoretical minimum angle and quantification were deduced,at the same time,these simplified relationship formula was proposed.The constraint conditions and theoretical minimum angle resolution of 29 kinds of scaners is caculated.The conclusion have directly significance on the angular resolution's calculation and the scanning interval setting.