In this work, Multiwall carbon nanotubes (MWCNTs) and carbon dots (CDs) were used in the preparation of electrochemical sensors. In the first step of the project, carbon dots were synthesized in an autoclave inside the furnace from chitosan. The product formation proved by using fluorescence method, FTIR, etc. In the next step, the treated pencil graphite electrod was placed in suspensions consist of MWCNTs, CDs and positively charged poly electrolyte, poly diallyldimethylammonium chloride (PDDA). Methadone oxidation followed by cyclic voltammetry and electrochemical impedance. The morphology of the electrode surface was studied by FE-SEM images. The modified electrode by PDDA-CDs-MWCNTs nanocomposite was chosen to use in the following steps. The effective parameters on sensitivity of method were optimized with two techniques: cyclic voltammetry and differential pulse voltammetry. The calibration curve was achieved with linear dynamic range 0.1-225 µM, detection limit 0.02 µM and relative standard deviation 1.8%. The capability of the proposed method was examined for methadone measurement in plasma and urine samples using recovery percent.