Over the past 30 years, China's total area sown with crops did not change significantly. Meanwhile, the occurrences of crop pests and diseases as well as the control (treatment) areas have increased drastically. China has become the world's largest pesticide manufacturer and consumer since 2005 and the up-trend is expected to continue. Correspondingly, the greenhouse gases (GHGs) emission resulting from pesticide usage may also increase fast and become an important part of indirect GHGs emission in agriculture. However, domestic GHGs emission parameters from pesticide usage were rarely reported in analysis of China's agricultural life-cycle, which leads to considerable uncertainty in studies related to agricultural indirect GHGs emission. In this study, GHGs emission from pesticides manufacture was estimated by summing up the global warming potential of GHGs emitted from four processes including manufacture of active ingredients, formulation of emulsifiable oils/wettable powders/granules, packaging, and transport. According to the occurrence of pests and diseases in six major crops (wheat, rice, maize, potato, oilseed rape, and cotton) in China, the amount of current GHGs emissions induced by usage of insecticides and fungicides specific for these crops was assessed based on the integration of available information on the use of relevant pesticides and GHGs emissions from their manufacturing. Our estimation indicated that the GHGs emission pertaining to pests and diseases control was the highest for rice and cotton (20.54 [2.03-50.95] and 19.51 [5.11-49.01], respectively) followed by oilseed rape (10.84 [8.10-13.62]), maize (10.38 [3.45-19.32]), wheat (9.19 [1.86-23.24]), and potato (5.91 [2.15-18.34] kg carbon equivalent [CE] per hectare each year). Different crop pests and diseases contributed differently to crop's GHGs emission from pesticides usage: for maize and cotton, pests were the main contributors (especially maize borer, maize earworm, and cotton plant-bug); for oilseed rape and potato, diseases were the main contributors (especially potato late blight and rape sclerotinia rot); and for wheat and rice, pests and diseases both contributed equally to the total emission (especially wheat aphid, wheat midge, wheat red spider, wheat powdery mildew, wheat scab, rice plant hopper, rice leaf roller, rice striped stem borer, rice blast, and rice sheath blight). Meanwhile, as to the pesticide GHGs emission per unit yield, all four grain crops contributed far less than cotton and oilseed rape. Correspondingly, the overall emission due to the insect pests and diseases control measures for each of the analyzed crops in China was: 220.8 (44.7-558.4), 606.7 (60.0-1505.1), 336.4 (112.0-606.3), 30.9 (11.2-96.0), 79.5 (59.4-99.8), and 96.4 (25.2-242.2) Gg CE/a for wheat, rice, maize, potato, oilseed rape, and cotton, respectively, with a total amount of 1.37 (0.31-3.13) Tg CE/a. It should be noted that these results are underestimation of China's actual pesticide GHGs emission since the herbicides were not considered because of the unavailability of weed treatment data. Owing to the variation in the characteristics of crop pests and diseases control measures (including various conditions of crops, pests, and diseases, wide range of pesticide and fungicide choices and their legal dosage), non-negligible uncertainties still exist in our current bottom-up estimates based on farmer surveys. More accurate estimation requires implementation of top-down methods and data based on enterprise-level surveys.