近年來區塊鏈技術及其相關應用成為熱門焦點，區塊鏈最大的特色包含去中心化以及匿名性等特性，然而在這樣的分散式網路中我們很難判斷對方是否值得信賴，在數位憑證中我們透過可信賴第三方擔任憑證中心為用戶簽發金鑰憑證以此建立用戶之間的信賴關係，但在區塊鏈此種分散式網路中找到一個可信賴第三方實屬不易，並且可能會與區塊鏈去中心化之特性背道而馳，因此本研究參考PGP信任網與小世界理論的概念，建立一套可適用於分散式環境中基於聲譽的信任度評估機制，並將此機制結合智能合約實現一個信任度評估機制購物平台，目的希望用戶與陌生人交易前，可透過此機制計算出信任度，提供用戶做為參考，幫助用戶更容易判斷陌生人是否可信，以降低受騙風險。 / In recent years, the blockchain technology and its relevant applications become hot spots. The greatest feature of the blockchain is the decentralization. Nonetheless, it is difficult for us to judge whether the other person get involved in the decentralized network is credible. Furthermore, it is difficult to find a reliable third party in such a point-to-point network. Consequently, this paper refers to the PGP web of trust and the small world problem to establish a set of reputation-based trust evaluation mechanism for decentralized environments, we combine this mechanism with a smart contract to achieve a trust evaluation mechanism shopping platform, It is expected that achievements of the paper can facilitate people’s judgment regarding the reliability of strangers and reduce the risks of being deceived.