Abstract: A quality accident of post-grouting bored pile in deep sand stratum is discussed as an example. Based on field test data and field investigation, the causes of quality accident are analyzed from the aspects of design, investigation and construction. The analysis results show that the main causes of the quality accident are improper holing and hole cleaning technology, unreasonable grouting amount, grouting speed, grouting device and the insertion depth of grouting pipe. In view of these reasons, solving measures are put forward. Reverse circulation technology and twice grouting technology should be adopted when post-grouting bored pile is cleaned in deep sand stratum. At the same time, reasonable grouting amount should be ensured, and consistency between grouting pipe and hole forming depth should be checked. The research results can be used as reference in the design and construction of similar pile foundation engineering of post-grouting bored pile in deep sand stratum.