Abstract: raw Lentinus edodes were homogenized by the traditional method and the improved method, then formaldehyde was distilled from homogenate and its content was detemined by high performance liquid chromatographythe (HPLC). In the improved method of sampling preparation, all the operation except of heat treatment was conducted in ice bath and e enzymes were deactivated in boiling water bath for five minutes after the sample was homogenized. The results show that the content of formaldehyde obtained by the improved method is significantly lower than that obtained by the traditional method and closer to the real content. The precision of the improved method is 93.53% and recovery of standard addition is 96.97%～99.00%. It can be concluded that the improved method of sampling preparation meets the requirment of the common quantitative detection.