In the transaction processes via an e-commerce platform, buyers will select not only a seller with high reputation, but also a platform with high reputation. Existing research mainly investigated seller reputation and have achieved some results, but the importance of e-commerce platform reputation is neglected. Although some scholars have discussed this construct theoretically, the lack of valid e-commerce platform reputation measurement scale makes it impossible to quantitatively study its antecedents and consequences, and then further advances are hindered by it. To address this omission, the investigation reports a series of 4 studies, and develops a multidimensional scale consisting of 4 dimensions ( cognitive reputation of platform enterprise, affective reputation of platform enterprise, cognitive reputation of sellers, and affective reputation of sellers) which shows good internal consistency and construct validity in subsequent analyses. This scale reflects unique facets of e-commerce platform by incorporating the value co-creation between platform enterprise and its sellers. It provides a more accurate e- valuation index system for e-commerce platform reputation, a reference for innovation of reputation measurement, and also a requisite instrument for the comparative analysis between different platforms, and finally, new directions for future research a- bout the purchase decision of buyers, operation of sellers, and the development strategy of platforms in the field of e-commerce platform.