In this project, an electrochemical sensor based on Bi 2 WO 6 nanoparticles was used on the multiwalled carbon nanotube substrate to modify the surface of the glass carbon electrode. Morphological studies, structure, and surface characteristics of the modified electrode were using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, scattering energy, Fourier transform infrared spectroscopy, BET analysis, electrochemical impedance spectroscopy and cyclic voltammetry. This sensor is used to measure methotrexate and imidacloprid pesticide. Then, the effect of experimental and instrumental parameters on the response of the sensor to the two samples of methotrexate and imidacloprid such as pH, catalyst dosage, potential scanning rate, accumulation potential and time and differential pulse parameters were evaluation and optimized. For Methotrexate, the results showed the Methotrexate oxidation reaction under the adsorption control. At optimum conditions, pH= 3.0 and in the potential range of 0.6 to 1.1 V with respect to the silver/silver chloride reference electrode under the potential of 0.00 V and 300 s pre-condensation time with potential step of 20 mV, pulse height of 80 mV, and the pulse time of 40 ms was obtained by differential pulse voltammetry for methotrexate, two linear ranges of 0.1-4.0 and 4.0-40.0 ?mol L -1 and the detection limit of 0.08 ?mol L -1 respectively The modified electrode showed good reproducibility and reproducibility and was used to measure methotrexate in human blood plasma. Also, The modified electrode was also used to measure imidacloprid by cyclic voltammetry. The results showed that the imidacloprid reduction reaction was under diffusion control. For imidacloprid, in the optimum conditions, pH = 7.0 and in the potential range of -0.3 to -1.3 volts with respect to the silver/silver chloride reference electrode by applying a pulse width of 40 ms, pulse amplitude of 50 mV and step potential of 10 mV, two linear ranges of 0.02-0.4 and 0.4- 3.0 ?mol L -1 and detection limit of 0.013 ?mol L -1 was obtained. Finally, the proposed electrochemical sensor was used to measure the cucumber and tomato samples.