Abstract: Price manipulation attacks manipulate the on-chain prices of decentralized financial (DeFi) projects by altering the digital asset stock, thereby attacking their liquidation mechanisms to achieve improper profits. Nowadays, price manipulation attacks have emerged as the most significant security threats to the current decentralized financial ecosystem. To defend from the price manipulation attacks, the oracle obtains the exchange prices from the real world, which are difficult to manipulate. However, the maintenance expense of the oracle is very high due to frequent on-chain data update, making it challenging to meet industrial demand. To address these issues, this paper proposes a defense mechanism against price manipulation attacks. This mechanism utilizes off-chain prices to guide the identification of on-chain price manipulation behaviors and intercepts price manipulative transactions through a contract proxy. The mechanism reduces the frequency of price submissions and the cost of updating off-chain data on-chain through low-frequency price feeding. This compromise aims to balance the cost of defense against price manipulation attacks with the precision of identification. Based on the experimental findings, we have conclusively demonstrated that our innovative method substantially diminishes the overall maintenance cost by over 30%, concurrently achieving an outstanding success rate of 97.5% in effectively safeguarding against price manipulation attacks.