Extensive use of imidacloprid for suppressing the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae), has placed heavy selection pressure on the target insect. A systematic study was carried out to determine imidacloprid resistance dynamics and cross‐resistance. Data collected from a 3‐year study (2005–2007) showed that in 2005, the resistance levels in Nanning (Guangxi), Haiyan (Zhejiang), and Nanjing and Tongzhou (Jiangsu) populations ranged from 200‐ to 799‐fold compared with the susceptible strain. However, the resistance levels decreased to 135‐ to 233‐fold in 2007, after reduced application of the chemical. A laboratory population was challenged with imidacloprid in successive generations. After 23 generations, the resistance ratio had increased from 200‐ to 1 298‐fold. Continuous selection with imidacloprid could increase the resistance level even more than has already been developed in the population. Stopping selection with imidacloprid led to a rapid decrease of resistance from 759‐ to 114‐fold after 17 generations. Resistance levels then became stable without decreasing any further. A similar result was also obtained from a study involving a field population (resistance ratio = 625‐fold) collected from Tongzhou. At first, the population showed a rapid decrease in resistance right after imidacloprid selection was stopped, and then the resistance stabilized at a level of 105–129‐fold. More interestingly, resistance increased again when selection was resumed. In addition, the resistant strain selected with imidacloprid showed substantial cross‐resistance to imidaclothiz, thiacloprid, and acetamiprid, and slight levels of cross‐resistance to dinotefuran and thiamethoxam, but no obvious cross‐resistance to nitenpyram, buprofezin, and fipronil. The information from this study is valuable for formulating resistance‐management strategies against N. lugens.