Mythimna separata, the oriental armyworm, is a major agricultural pest of China. Five breeding regions are colonized successively by each generation of moths during the course of the year as a result of long-range migration. Three regions are colonized from south to north of China during the first half of the year and two in the second half of the year, possibly from north to south. The regularity of the seasonal displacements of the armyworm populations are an important basis for forecast and control. This paper presents a summary of research on migration of the oriental armyworm in China and discusses management strategies for this pest.