[Aim]  To clarify the barrier effects of different sized of insect-proof mesh on cowpea thrips, and to determine the impact of mesh on field microclimate, aiming to provide references for the selection and application of insect-proof screens. [Methods]  The effect of four sizes of insect-proof mesh on the abundance of cowpea thrips was measured and the effect of different sized mesh on aspects of the crop microclimate, such as light, ventilation, temperature and humidity, was measured using light meters, anemometers, and temperature and humidity recorders. [Results]  Eighty mesh insect-proof screen was the most effective barrier to cowpea thrips, with less than 10% of the thrips passed through, followed by the 60-mesh screen. Twenty and 40-mesh screens were relatively weak barriers. Considering the importance of excluding insects but also allowing adequate ventilation, the 60-mesh insect-proof screen was selected for field trials. The results indicate significantly lower thrip numbers than in an unscreened control site (P<0.01). Light intensity and wind speed inside the mesh were significantly reduced (P<0.01), with an average decrease in light intensity of 192.42 lx. Average wind speed at the edge of the mesh decreased by 0.59 m/s, and the average wind speed in the middle of the enclosure decreased by 0.86 m/s. The average wind speed between rows decreased by 0.98 m/s. Enclosing cowpea crops with insect-proof screens affects the temperature and humidity inside the enclosure. Compared to an open field, the temperature inside the mesh significantly increased between 12:00 and 20:00 (P<0.01). Average temperature increased by 2.81 ℃ at the edge of the enclosure, by 2.23 ℃ in the middle and by 3.09 ℃ between rows. Humidity inside enclosures significantly increased before 12:00 and after 20:00 (P<0.01), with an average increase of 4.66% at the edge, 7.11% at the middle, and 7.44% between rows. However, between 12:00 and 20:00, the humidity inside the enclosure significantly decreased (P<0.01), with an average decrease of 7.63% at the edge, 3.53% in the middle, and 5.80% between rows. [Conclusion]  The laboratory tests demonstrated that the 80-mesh insect-proof screen provided the best barrier effect against cowpea thrips. However, for practical field application, the 60-mesh screen is recommended as it balances the requirements of excluding pests with maintaining proper ventilation. Additionally, the use of insect-proof screen alters the microclimate conditions in fields, resulting in reduced light intensity and wind speed, along with noticeable variations in temperature and humidity during different time periods.