The Internet of Things (IoT) global market is growing significantly fast in recent years, from a wearable small watch to a giant airplane. The Smart-home is one of the most popular applications which can improve the resident's life quality. However, the security and privacy issues of homeowner bring emerging challenges while more and more data are collecting and sharing by the instances of different IoT devices within the Smart-home. Confront the challenge, an emerging charming technology blockchain provides a private, secure, and decentralized mechanism for the data usage. But, there are still many challenges for the application of blockchain such as the efficiency, storage, and energy cost, etc. This paper proposes IoT architecture in Smart-home environment based on blockchain and smart contract with the comprehensive consideration of the primary challenges. Our approach exemplifies the three core components in Smart-home: smart contract, private blockchain, and public blockchain. Each Smart-home contains their unique private chain. We present the application scenarios in our architecture and discuss the principles of blockchain smart contract application for Smart-home.