The invention discloses a construction method of a foundation pit group and a foundation pile group. The foundation pit group comprises three or more parallel deep and narrow staggered foundation pitswith the height difference exceeding 13 m; and the foundation pile group is distributed in the deep and narrow foundation pits of the foundation pit group, and performs crossed operation with the deep and narrow foundation pits of the foundation pit group. The construction method includes the following steps that a BIM structure model of the foundation pit group and the foundation pile group is built; according to the BIM model, colliding detection is performed; the foundation pit group is divided into a narrow area and a deep area, and then the narrow area is divided into an influence area and a non-influence area; earthwork excavation is performed to an operation face; supporting pile construction of the deep area is performed; foundation pile construction of the influence area of the narrow area is performed; foundation pile construction of the deep area is performed; earthwork excavation and anchor rope construction of the deep area are performed, and foundation pile constructionof the non-influence area of the narrow area is performed at the same time; and local deep pit micro pile, micro pile anchor rope and micro pile top crown beam construction of the deep area is performed. The construction method is a fast, efficient, economical and reasonable continuous multi-segment large-height-difference long and narrow deep foundation pit group and foundation pile group construction method.