With the widespread adoption and efficient utilization of distributed energy resources, the deployment scale of smart terminals in the power Internet of Things continues to expand. The disorderly and variable power services increase dramatically, making it difficult to process high-priority tasks in a timely and reliable manner. To address this issue, an optimized model for the Power Internet of Things (PIoT) based on blockchain technology is proposed. The model introduced a high-priority trusted small-area mechanism. It calculated server trust values based on historical interaction information and intelligently offloaded high-priority tasks to nodes with high trust values and strong computing capabilities. The method utilized blockchain technology to build a decentralized distributed ledger system. This system ensured data security and reliability during task offloading by preventing malicious nodes from tampering with transaction information. The algorithm made a matching strategy between task computation and consensus process to address their parallel characteristics. It optimized computing resource allocation to reduce delays caused by the consensus process. This paper presented an Improved Genetic Particle Swarm Optimization (IGPSO) algorithm. The algorithm took the weighted sum of network cost and priority mismatch penalty factor as the fitness function. It achieved joint optimization of task offloading decisions and computing resource allocation. The simulation experiment showed that the strategy achieved performance optimizations of 9.71%, 85.71%, 79.73%, and 56.82% in total system cost, system energy consumption, delay of high - priority tasks, and success rate respectively. This proved the effectiveness of the solution.