Abstract: Based on population genetics, we devised a procedure of single pair selection for studying a method of rapid obtaining resistant strain.Resistance to lambda-cyhalothrin was mass selected in laboratory with 4.9-fold increase of LC50 in cotton bollworm compared with control population. We studied the role of single pair selection on speeding up resistance selection to lambda-cyhalothrin in cotton bollworm. Comparing single pair selection with mass selection, the resistance ratio to lambda-cyhalothrin increased to 27.3-fold from the original 4.9-fold after 2 generations' single pair selection, whereas the resistance ratio to lambda- cyhalothrin only increased to 7.4-fold from the original 4.9-fold after 2 generations' mass selection. The result shows that it is beneficial for speeding up resistance selection to alternate a few generations single pair selection in mass selection.