Environment settlements always occur while tunnel constructs in cities, which may cause ground collapse and building damage. It is engineering significant to analyze the key factors in the tunnel construction for an acceptable environment settlements value. The Rough Sets and the settlements induced by the tunnel construction were reviewed, and 22 engineering samples were investigated on the 9 condition attributes to 1 decision attribute. The significant degrees of the 9 condition attributes are normalized, and the importance of the condition attributes is obtained based on the normalized value. The results offer a method to extract the key factors on environment settlements in tunnel construction based on Rough Sets.