Objective To study effects of different irrigations on the recurrence of chronic rhinosinusitis after functional endoscopic sinus surgery. Methods From Apr. 2015 to Apr. 2016, a total of 66 patients with chronic rhinosinusitis in our hospital were taken as the clinical research objects, and they were randomly divided into control group and observation group. Both groups accepted nasal irrigation treatment by 500mL normal saline after functional endoscopic sinus surgery, besides, the observation group was given additional 10mg dexamethasone. The main symptoms and signs were compared between the two groups before treatment, 2 and 4 weeks after treatment; the total effective rates of the two groups were also compared; and the recurrence rates of the two groups were observed after 3 months follow up. Results 2 and 4 weeks after treatment, the scores of symptoms in the observation group were respectively (3.24±1.28) and (2.13±1.15) which were not only lower than those in the control group (4.36±1.14) and (3.57±1.27), but also lower than before treatment, and their differences were statistically significant (P<0.05), the scores of signs in the observation group were respectively (4.02±1.19) and (3.42±0.96) which were not only lower than those in the control group (4.83±1.22) and (4.02±0.85), but also lower than before treatment, and their differences were statistically significant (P<0.05). The total effective rate in the observation group was 90.91% which was higher than that in the control group 69.70%, and the recurrence rate in the observation group was 15.15% which was lower than that in the control group 42.42%, and their differences were statistically significant (P<0.05). Conclusion: Nasal irrigation treatment after functional endoscopic sinus surgery for chronic rhinosinusitis can obviously improve patients' clinical symptoms and signs and reduce recurrence rate, and the irrigation of dexamethasone and normal saline has better effect.