The under ground metro of Cairo has its important role in the life of cities and its zones. It has various effects on city components and human activities especially in big cities like greater Cairo which involve a lot of informal settlement and also many problems. Since 1987 the metro play its important role in solving traffic problems , and it was considered that metro has a lot of positive effects on urban agglomeration specially in surrounding zones , but after 17 years it was found that a lot of negative effects has occurred in urban agglomeration because of metro specially in informal settlements in fringes. This paper aims to count and clarify these negative effects as a result of the penetration of metro line through these areas. The paper also trying to find most appropriate solutions to ignore or reduce the influences of these effects through a group of tools to control the urban mass of informal settlements specially these once attached directly to the metro line path