In the background of high counting rate, the full-energy peak of X-rays fluorescence is seriously disturbed by the false peak whichis caused by the charge sensitive preamplifier in High Performance Silicon Drift Detector and slow digital shaping algorithm. In this paper, a novel method of false peak eliminating is presented. And some technical points are also introduced in details such asdigital triangleshaping, signal screening and peak discrimination. Taking 55Fe nuclide and rock samples as experimentations, the spectrum before and after the false peak eliminating are compared. And the results showed that the false peak can availably be eliminated. Therefore, the performance of fine X-rays fluorescence will be improved such as peak to background ratio and accuracy of trace elements analysing.