The invention discloses a preparation method of solid phase peptide synthesis triptorelin, which includes the following steps: with Rink Amide AM resins or Rink Amide MBHA resins as starting materials, amino acids with protective groups are sequentially connected according to solid phase synthesis, so as to obtain protective decapeptide resins, and meanwhile crude products are obtained by sequentially removing Fmoc-protective groups and synchronously removing side-chain protective groups and cutting peptides, and triptorelin elaborate products are prepared after the crude products are separated and purified by C18 (or C8 ) column and freeze-dried. The preparation method is stable in technology, convenient in raw and auxiliary material sources, short in production cycle, high in yield, stable in quality, low in production cost and high in transpeptidase yield. Besides, as the preparation method avoids using poisonous reagents, such as hydrogen fluoride, and the like, the pollution of three wastes is low, purification yield is over 25 percent and each step of transpeptidase yield is above 98 percent; the yield after cutting peptides is 78.8 percent and the total yield is 25.4 percent.