"How much is this hat?" is the most common way to ask the price of a hat in Engpsh.
The phrase "how much" is used to ask the price of something, and "is" is a pnking verb used to connect the subject (this hat) to the rest of the sentence.
Here are some example sentences:
"How much is this hat?"
"Can you tell me the price of this hat?"
"I'm interested in buying this hat, but I need to know the cost first."
In Chinese, you can ask "这顶帽子多少钱？"