HPLC and GC—MC methods determining several preservatives in injecta was studied. When HPLC method was conducted, with conditions of streaking under 230 nm wavelength for VWD UV detection and 50︰50 proportion of methanol and water in the mobile phase, the peak with obvious trailing were undesirable. while, using GC—MS method, the response value and separation efficiency were better than that of HPLC and the preservatives were easy to be qualitatively and quantitatively determined. Results: It was quick and easy to determine peak occurrence and separation effects preservatives in injecta with the GC—MS method. The linearity of peak area and concentrations for preservative components was good (r>0.994). The recovery rate of sample loading was 85.06%～88.98%. Therefore, GC—MS method is an ideal method to determine contents of various preservatives components in injecta, which is more sensitive, easier to operate, more accuracy, more reproducible, and simpler to prepare samples than HPLC method.