【Background】In recent years, global climate change continually, and it has a great influence on the farmland ecosystem and insect pests. 【Method】How climate factors (average temperature, relative humidity and rainfall) in January to August from 2009 to 2013 affect population densities of non-target pest species in the two kinds cotton fields were systematically determined in field plot at Anyang, Henan Province. 【Result】For the cotton aphid (Aphis gossypii), the average populatin density was correlated with temperature from January to August but not relevance with relative humidity and total rainfall. For the cotton leafhopper (Empoasca biguttula), the population density positively correlated with the rainfall from January to April, and negatively correlated with relative humidity from January to August. For the cotton whitefly (Bemisia tabaci), population density was negatively correlated with rainfall from May to August. The average temperature May to August, whereas relative humidity from May to August negatively affected Thrips tabaci population density. Mirids in the cotton fields are probably affected by a combination of climate factors. 【Conclusion and significance】Non-target pests in the conventional and Bt cotton fields responded similarly to these climate factors. These results can provide a theoretical basis for forecasting population dynamics of pests, playing a very important guiding role in the prevention and treatment of cotton pests.