Abstract: Power data trading is an important way that data can play valuable role. However, there exists considerable problems in the present data trading, such as centralized trading trust, unclear trading rules and difficult transaction supervision. This paper proposed power trading scheme based on blockchain. Firstly, upon the analysis of the characteristics of power data and the problems encountered in power data trading, the applicability of block chain to power data trading scenarios is expounded. Then, the basic characteristics and classification of block chain technology are described. Next, the design details for intelligent contract are put forward to ensure the secure and automatic execution of power data transaction. Finally, in combination with consensus mechanism, transaction account and other factors, the blockchain-based power data transaction is proposed including its basic framework and especially the analysis of key supporting technologies to ensure the operation security and smoothness of power data trading.