In recent years， floating accidents in building engineering have been reported frequently， and the existing judicial precedents are extremely unfavorable to the investigation and design units. Starting from the principle of anti-floating， based on the analysis of existing cases， combined with the requirements of relevant standards and problems in practice， this paper puts forward suggestions on the concerns of investigation and design documents on anti-floating. The dynamic and process explanation of “basin effect” is given for the first time in this paper. The basin-in-basin technical measures have been put forward for the first time. Automatic monitoring， alarm systems， among others are suggested for large-scale foundation pits. This paper is intended to clarify the investigation and design conditions， avoid engineering accidents， legal disputes and the adverse results caused by them， which can be used for reference by investigation and design units.