A method based on microwave digestion and inductively coupled plasma-atomic emission spectrometry (ICP-AES) was established for simultaneous determination of eight trace elements (K, P, Ca, Mg, Cu, Fe, Zn, Mn) in Cordyceps militaris. Samples were digested with HNO3 and H2O2 as digestion agent under the optimized condition. The working curves were established based on the principle of low detection limits, high sensitivity and less substrate element disturbance. Finally, the contents of above eight inorganic elements in Cordyceps militaris were simultaneously determined under the proposed condition. Good linearity of the working curves for the eight elements was obtained in this study. The recovery rates obtained by determining reference matter (pork powder) method were between 91%-106%, and the relative standard deviations (RSD) were lower than 3.0%. The recovery rates obtained by standard addition method were between 90%-108%, and RSD were lower than 3.0% likewise. It suggests that this method was accurate and reliable for simultaneous determining the eight trace elements existed in Cordyceps militaris. In addition, the analysis results showed that Cordyceps militaris was rich in inorganic elements such as K, P, Mg, Ca, Zn, especially K and P. Furthermore, the relationship between the essential inorganic elements and its particularly medical effects were discussed in this paper.