NOVELTY - Synthesizing ethyl cyclopentene alcohol ketone, comprises: (a) mixing 56.4 g sodium hydride with 250 ml dried ethylbenzene; (b) reacting the solution; (c) stirring the solution and dropping in 120 g ethane; (d) decompressing the solution; (e) dissolving the middle reactant; and (f) mixing the product prepared in the last step with 3200 ml hydrochloric acid.    USE - The method is useful for synthesizing ethyl cyclopentene alcohol ketone (claimed).    ADVANTAGE - The course of production of the ethyl cyclopentene alcohol ketone is safe and reliable, the product is difficult to oxidize in the course of production, and the conversion efficiency is high with little pollution, and industrialized operation is convenient.    DETAILED DESCRIPTION - Synthesizing ethyl cyclopentene alcohol ketone, comprises: (a) mixing 56.4 g sodium hydride with 250 ml dried ethylbenzene, stirring and adding in 174 g dimethyl adipate, reacting completely at 100 degrees C, then reducing temperature to 50 degrees C, under pressure of negative 0.04 MPa to negative 0.05 MPa, decompressing and steaming out alcohol compound; (b) reacting the solution which the alcohol compound has been removed at top temperature of 85-105 degrees C, kettle temperature of 100-130 degrees C for 3 hours, then reducing the temperature of the reaction solution to room temperature; (c) stirring the solution and dropping in 120 g ethane, stirring to react for 2 hours at temperature of 70 degrees C; (d) decompressing the solution at temperature of 112 degrees C, and pressure of negative 0.06 MPa to negative 0.07 MPa to recycle ethylbenzene, after cooling, adding in 500 ml water to rinse, then extracting aqueous solution with 100 ml ethylbenzene, after removing ethylbenzene, the middle reactant 2-ethyl-2-cyclopentanone carboxylic acid methyl ester is prepared; (e) dissolving the middle reactant in 1000 ml acetic acid, at room temperature passing in 250 g hydrogen chloride, and stirring to react for 1 hour, then steaming out 400 mg acetic acid, the product 5-dichloro-2-ethyl-2-cyclopentanone carboxylic acid methyl ester is prepared; and (f) mixing the product prepared in the last step with 3200 ml hydrochloric acid whose concentration is 12-15%, heating up to 100-110 degrees C, stirring to react for 8-12 hours, after cooling the reaction solution, extracting the organic solvent with 700 ml ethyl acetate, then decompressing the prepared solution at temperature of 55 degrees C, pressure of negative 0.04 MPa to negative 0.05 MPa to recycle the ethyl acetate, recycling the remained solution and decompressing at temperature of 125 degrees C, pressure of negative 0.095 MPa to negative 0.1 MPa to distill, then the final product is prepared.