NOVELTY - Preparing pesticide nitenpyram, comprises synthesizing 1,1,1-trichloro-2-nitroethane from 1,1,2-trichloroethane by elimination and catalytic nitration reaction, preparing N-(2-chloropyridin-5-yl)methylethylamine by reacting 2-chloro-5-chloromethyl pyridine and ethylamine in water as solvent in presence of a phase transfer catalyst, condensing N-(2-chloropyridin-5-yl)methylethylamine with 1,1,1-trichloro-2-nitroethane in dichloromethane solvent in presence of an acid-binding agent and phase transfer catalyst, reacting the condensate product with methylamine, and processing.    USE - The method is useful for pesticide nitenpyram (claimed).    ADVANTAGE - The method has high yield and product purity and short process flow; produces little environmental pollution; and is economical and suitable for industrial production.    DETAILED DESCRIPTION - Preparing pesticide nitenpyram, comprises (i) reacting 1,1,2-trichloroethane with sodium hydroxide solution at -15 to 100 degrees C to obtain vinylidene chloride; (ii) nitrating vinylidene chloride by using hydrochloric acid and nitric acid in the presence of catalyst A1, separating and purifying to obtain 1,1,1-trichloro-2-nitroethane, where the catalyst A1 is Zeolite Socony Mobil (ZSM)-25 molecular sieve, beta 2 zeolite molecular sieve, silicoaluminophosphate (SAPO211) molecular sieve, ammonium (NH4)-Y molecular sieve, rare earth-Y molecular sieve or SSY molecular sieve; (iii) reacting 2-chloro-5-chloromethyl pyridine with ethylamine at -10 to 50 degrees C by using water as solvent in presence of phase transfer catalyst A2, desolventizing reaction product, alkali washing and distilling to obtain N-(2-chloropyridin-5-yl)methylethylamine, where the phase transfer catalyst A2 is tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, trimethyl benzyl ammonium hydroxide, triethyl benzyl ammonium chloride, tetrabutyl ammonium bromide or cetyl trimethyl ammonium bromide; (iv) condensing N-(2-chloropyridin-5-yl)methylethylamine with 1,1,1-trichloro-2-nitroethane in dichloromethane solvent in the presence of an acid-binding agent and phase transfer catalyst A2 at -10 to 50 degrees C to obtain condensate compound 1-chloro-N-((6-chloropyridin-3-yl)methyl)-N-ethyl-2-nitroethenamine, where the acid-binding agent is sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide or potassium hydroxide; and (v) adding aqueous methylamine solution to the condensate compound in the same reaction kettle at -10 to 50 degrees C, performing amination, extracting the reaction product, desolventizing, and recrystallizing.