Abstract: The first nozzle structural parameters of air-jet spinning machine mainly include jet orifice obliquity,nozzle inside diameter,jet orifice number.In order to explain the effect of these structural parameters on yarn strength,experiments and regression analysis are undertaken to investigate the effect of the first nozzle structural parameters on air-jet spun yarn strength.The conclusion is drawn that the first nozzle structural parameters have great impact on the yarn strength.And when jet orifice obliquity is(42.9°,) nozzle inside diameter is(0.4 mm,) jet orifice number is 4,the strength of air-jet spun yarn is the highest.