Abstract: This paper describes the laws and principles of the commonly-used optical illusions in mapmaking,and studies how to apply these laws and principles to mapmaking scientifically,correctly and rationally.By using optical illusions rationally,"leave mistake uncorrected and make the best of it",not only the noise of cartographic communication can be reduced,the confusion on the cartographic communication caused by optical illusions can be removed,the effect of cartographic communication can be promoted,but also the express of map can be promoted,the function of map loaded with information can be improved.It provided a scientifical basis for the best design of map.