The invention relates to the field of environment-friendly, energy-saving and emission-reducing electrochemical synthesis, in particular to a method for preparing 2,3,5,6-tetrachloropyridine in a cathode chamber and diglycolic acid in an anode chamber based on bipolar membrane technology. The method is characterized in that the electrolyte in the cathode chamber contains 0.5 mol/L of aqueous solution of pentachloropyridine tetrahydrofuran sodium acetate and 3 to 10 g/L of tetramethylammonium bromide; the electrolyte in the anode chamber contains 100 g/L of diglycol, 2 mol/L of NaOH solution and 50 to 500 g/L of MnO2; the electrolysis temperature is between 20 and 65 DEG C, the current density is between 16 and 36 mA.cm<2>; and the electrolysis time is 40 to 80 minutes. The preparation method is environment-friendly, has mild production conditions, and achieves the effect of energy conservation; and the yield sum of the cathode and anode chambers is more than 100 percent.