Background: Venous thromboembolism (VTE) is a severe preventable complication among ophthalmic surgical patients. The knowledge, attitude, and practice (KAP) of nurses play a key role in effective VTE prevention. However, little is known about the KAP of ophthalmic nurses' VTE prevention. This study aimed to examine the level of KAP toward VTE prevention among Chinese ophthalmic nurses and to investigate the influencing factors of their VTE practice. Methods: A total of 610 ophthalmic nurses from 17 cities in Hunan and Zhejiang Provinces, China, participated in this study. Data was collected via the Sojump online platform from March to April 2021. A self-administered VTE questionnaire was developed to assess nurses' KAP toward VTE prevention. Multiple linear regression analysis was used to analyze the influencing factors of ophthalmic nurses' VTE prevention practice. Results: The scores (correct rates) of ophthalmic nurses' knowledge, attitude, and practice were 103.87 ± 20.50 (76.4%), 21.96 ± 2.72, and 48.96 ± 11.23 (81.6%), respectively. The three lowest-scored knowledge items were related to VTE complications, physical prevention, and risk assessment. The three lowest-scored attitude items were related to nurses' training, VTE risk, and patient education. The three lowest-scored practice items were related to the assessment scale, VTE assessment, and patient education. Nurses' knowledge, attitude, and practice were significantly correlated with each other. Multiple linear regression analysis showed that Hunan Province (B = 2.77, p = 0.006), general hospital (B = 2.97, p = 0.009), outpatient department (B = 3.93, p = 0.021), inpatient department (B = 2.50, p = 0.001), previous VTE prevention training (B = 3.46, p < 0.001), VTE prevention management in hospital (B = 4.93, p < 0.001), better knowledge (B = 0.04, p = 0.038), and positive attitude towards VTE prevention (B = 1.35, p < 0.001) were all significantly and positively associated with higher practice scores in VTE prevention. Conclusions: Our study provided a comprehensive understanding of the ophthalmic nurses' knowledge, attitude, and practice in VTE prevention, as well as identified specific items in each dimension for improvement. In addition, our study showed multiple factors were associated with ophthalmic nurses' practice in VTE prevention, including environmental factors, training and management, knowledge and attitudes toward VTE prevention. Our findings provide important implications and guidance for future intervention programs to improve the ophthalmic nurses' knowledge, attitude, and practice in VTE prevention.