A method for regulating sample surface charge has been proposed in this invention. The processes of applying a charged particle beam to a first area and applying a flood energized beam gun with gaseous molecules to a second area are executed in the method when the sample is in both continuous and Leap & Scan movements. The second area is located at a predetermined distance from the first area behind or ahead of the first area being scanned with respect to the movement of the sample. Thus, the surface of the sample may be regulated.