With the advent of 5G high-bandwidth and low-latency era, mobile data traffic has exploded. Most of the current researches on task offloading in edge cloud environments mainly focuses on minimizing latency, energy consumption and cost.But problems such as resource supply and demand relationship in the actual cloud market, participants’ malicious competition behavior and task mobility will affect the actual offloading results, and the security of the offloading process cannot be guaranteed. Therefore , an Auction Based Location-aware Task Offloading (ABLTO) strategy is proposed, which uses the combined double auction model to meet users’ needs for various types of resources. Then the buyer sorts according to its bid density, and the seller is ranked according to the authenticity of its bid and the distance from the buyer, and incentive/punishment measures are set to encourage the seller to deliver in good faith. The auction is deployed in the smart contract to ensure the authenticity and reliability of the process. Finally, the authenticity, fairness and economic benefits of the strategy are verified through simulation experiments.