【Objective】The regularity of disease and insect pests incidences in cowpea plantations were compared in greenhouse and open field conditions to develop proper disease and insect pests control measures in Hainan. 【Method】Cowpea cultivation experiments were conducted separately in open field and greenhouse during winter in 2010-2011 and spring and summer in 2011 to investigate the presence of diseases and insects pests such as Prodenia litura， bean-pod borer， Liriomyza sativae， thrip， leaf mite， powdery mildew， rust disease， ring rot， and black leaf mold， etc. 【Result】The initial population number of Prodenia litura， bean-pod borer， Liriomyza sativae and thrips in greenhouse was lower than those recorded in open field conditions. The initial population number of thrips was high at all growth stages of cowpea， i.e.， thrips were the main insect pest which affected cowpea growth and development. Rust and ring rot diseases were identified as the major diseases and these were significantly more severe in cowpea planted during spring and summer of 2011 compared to cowpea cropped during the winter of 2010-2011. 【Conclusion】Under green house conditions， the insect and pests can be controlled， however no significant differences were observed in disease incidences in greenhouse and open field conditions.