Disclosed is a method for preparing a Glecaprevir synthetic intermediate. An epoxy cyclopentane is used as a starting material to carry out a ring opening reaction to form 2-hydroxy-1-propenyloxycyclopentane, the same being acetylated to obtain 2-acetoxy-1-propenyloxycyclopentane. The 2-acetoxy-1-propenyloxycyclopentane is subjected to resolution and then activation and amino condensation in sequence to obtain a Glecaprevir synthetic intermediate. The disclosed method has fewer reaction steps, and higher yield. The total yield is higher than 30% on average and is much higher than the 10% yields in the prior art. The method is also low in cost, environmentally friendly, has mild in reaction conditions, is simple to operate, and suitable for industrialization. Further disclosed is a preparation method for a Glecaprevir synthetic intermediate amine salt likewise featuring high yields, mild reaction conditions, and simple operation.