In view of the problems such as slurry leakage, low drilling efficiency and difficult hole formation in the construction of cutoff walls in the upstream and downstream cofferdams of TB hydropower project, based on the successful construction experience of cutoff walls in previous projects, From three aspects: construction scheme and process, quality control measures, quality inspection and evaluation, the pre-control measures and continuous improvement measures taken in the construction of cutoff wall of TB hydropower project are introduced. It is believed that the measures taken ensure the quality of the project and ensure the construction safety, quality and progress.