Ribose-phosphate pyrophosphokinase 1 (PRPS1) was identified and isolated as a differentially expressed gene between deltamethrin-susceptible (DS) and deltamethrin-resistant (DR) Culex pipiens pallens and Aedes albopictus C6/36 cell line through microarray and 2D-Gel. An open reading frame of PRPS1 cloned from C. pipiens pallens has 1,011 bp and encodes for a 336 amino acids protein which shares high homology with Culex quinquefasciatus. Real-time polymerase chain reaction was used to determine the transcript expression level of PRPS1 in DS and DR strains. The expression levels of PRPS1 were higher in DR laboratory strains and natural population JXZ-DR, JXZ-LDR. PRPS1 was also detected and expressed at all developmental stages of C. pipiens pallens and increased expression level in DR3 strain than DS strain in the third and fourth instar larvae, female and male stages. In addition, to further investigate the role of PRPS1 in deltamethrin resistance, PRPS1 was transiently expressed in A. albopictus C6/36 cells and detected by western blotting. Cells transfected with PRPS1 had an increased resistance to deltamethrin compared with control cells. These results suggested that the increased expression level of PRPS1 may play roles in the regulation of deltamethrin resistance.