In this thesis, sol–gel process is used for manufacturing of polydimethylsiloxane adsorbent on stir bar. After that chlorpyrifos pesticide was extrated by the stir bar sorptive extraction (E), and determination by Ion mobility spectrometry. An injection port was constructed for connecting of E technique to ion mobility spectrometry. In this project the dead volume of injection port is low so that the sample leaves the injection port and quickly enterd to the ion mobility spectrometer. Therefore, the peak broading can be minimized. The effected parameters on the extraction efficiency including stirring rate, extraction temperature, salt addition, extraction time, desorption temperature and pH were optimized. The best extraction efficiency was observe at 400 rpm stirring rate, extraction Temperature was 35?C, extraction time was 15 min, desorption temperature 180?C and pH was 2. Agricultural wastewater, watermelon and river water were selected as real samples. linear dynamic range was obtained from 2.0-150.0 ?g/L and correlation coefficient (r 2 ) was 0.9976 and 0.9973, For agricultural wastewater and river samples, respectively. Linear dynamic range was obtained from 12.5 to 250 ?g/kg and r 2 equal 0.9994 for watermelon sample. The limit of detection was obtained to be 0.6?g/L for the real water sample and 0.4 ?g/L for watermelon. The intra- and inter-day relative standard deviations were calculated to be 6 and 3%. The recovery values were calculated 111, 99 and 97 for the agricultural wastewater, river water and watermelon, respectively.