It was found that Ag nanoparticles (NPs) could enhance the chemiluminescence (CL) intensity of luminol- potassium ferricyanide system. On the basis of enhancement effect,a flow injection method was developed for the determination of terbutaline sulfate. The structure and shape of Ag NPs were characterized by transmission electron microscopy. The UV-Vis absorption spectra and chemiluminescence spectra suggested that new luminophor was not formed after Ag NPs introducing in luminol-potassium ferricyanide chemiluminescence system. A possible mechanism of Ag NPs strengthening on luminol-potassium ferricyanide CL reaction was also discussed. The effect of concentration of luminol,potassium ferricyanide,sodium hydroxide and Ag NPs on CL reaction was investigated respectively. In the optimum conditions,the linear range was 1.0×10~(-9) -2.0 ×10~(-5) g/L(r =0.9935) and the detection limit was 1×10~(-10) g/L. The relative standard deviation (RSD) was 3.6% for 1. 0 ×10~(-6) g/L terbutaline sulfate (n = 11 ). The recommended method has been successfully applied to the determination of terbutaline sulfate tablets and the recovery was between 98. 5% - 102. 5% ,moreover the results were almost identical with the same results of Pharmacopoeia method.