In financial statement the purchase take or record in expense side in income statement but on the other hand purchase is my asset because anything comein my account than this thing is debit

If I understand your question, you are asking about the Purchases account used in a periodic inventory system. In this system, all purchases are posted by a debit to this account during the accounting period. At the end of the period, the Purchases will be zeroed out, with the costs being split between Inventory (an asset on the Balance Sheet) and Cost of Goods Sold (an expense on the Income Statement).

If that is not what you are asking, please try to rephrase and I'll see if I can help you. Thanks.