A miniaturized method based on solid phase extraction was presented for the preconcentration and determination of diazinon and fenitrothion. Diazinon and fenitrothion were preconcentrated on electrospun nanofibers as an adsorbent and then monitored by high performance liquid chromatography with diode array detector (HPLC-DAD) system. Some important parameters influencing the extraction efficiency, such as fiber packing amount, elution solvent, pH, and ionic strength of the sample solution were investigated. Under optimized conditions, the calibration curve was linear in the range of 0.5-50.0ngmL(-1) with a regression coefficient of 0.996 and 0.998 for diazinon and fenitrothion, respectively. The limits of detection (S/N=3) were 0.09 and 0.07ngmL(-1) for diazinon and fenitrothion, respectively. This analytical method will be useful for the analysis of diazinon and fenitrothion in tap water with high precision and accuracy.