This study systematically investigated the mechanism of the effect of polyacrylamide (PMA) concentration on the flocculation and settling behaviour of waste sludge generated from a drilling project in Xiaoshan. The effects of different PMA dosages on sludge separation efficiency and settling behaviour were investigated by laboratory experiments. The experimental results showed that lower dosages of poly (methyl methacrylate) (PMA) resulted in faster initial separation and more stable long-term flocculation, while higher dosages resulted in faster flocculation but lower long-term stability. This study innovatively optimised the treatment of waste sludge by determining the optimal PMA dosage and balancing flocculation rate and settlement stability to improve sludge treatment efficiency. These findings provide practical guidance for similar environmental engineering applications.