<strong>Purpose: </strong>To investigate the effect of ultrasound-guided unidirectional valve cleft enlargement in the treatment of popliteal cysts. <strong>Methods: </strong>Forty-eight patients with popliteal cysts who met the inclusion criteria and were admitted to our hospital from December 2018 to June 2020 were randomly divided into group A (24 cases) and group B (24 cases). Group A was treated with a central venous catheter dilator, and group B was treated with traditional open surgery to remove the popliteal cyst. Visual analogue scale (VAS) was used to evaluate discomfort. The VAS, Lysholm score of knee joint and Rauschning-Lindgren grade 0~I improvement rate were compared at 6 months after operation. <strong>Results:</strong> The postoperative VAS in group A was significantly better than that in group B (P < 0.05), and the postoperative Lysholm score and Rauschning-Lindgren grade 0~I in group A were higher than those in group B (P < 0.05). There was no recurrence or other complications in either group. <strong>Conclusions:</strong> Ultrasound-guided central venous catheter dilator is more effective than traditional surgical resection of popliteal cysts.