Customs duty fee when importing from China

I'm importing clothing products from china and i'm getting cutsoms duty fee. value of shipment is $250 and im getting customs fee for $250 as well. thats 100% mark up
i'm receiving two shipments and both are same amount value and same customs fee.
shipments are a week apart
can someone tell me along the process what gone wrong and how can i avoid customs duty fee or at least reduce the amount.
thanks!!

Ask your supplier to label the value lower than 50 USD