This thesis talks about the harassing people from square dancing,in order to reduce the negative effects,the first research step is a survey of squares allocation,includes the kinds and the features of the urban recreational squares,the facilities,activity crowds' composition and main exercises contents in squares,then this paper analyzes the negative effect from the crowd activity in squares,such as noise nuisance,poor sanitation,facilities easily damaged. At the end,the article proposes some countermeasures to reduce the external interference.