A judgment method for hardware compatibility is disclosed. The judgment method is operated with a first electrical device and a second electrical device having a plurality of transmission interfaces. The judgment method is started after the first electrical device electrically connected to one of the transmission interfaces of the second electrical device. The judgment method includes an interface information capturing process, a compatibility comparison process, a compatibility determination process and a recommendation execution process. In the interface information capturing process, the interface information of the transmission interface of the second electrical device connected to the first electrical device is captured. In the compatibility comparison process, the interface information is compared with a compatibility database to obtain a comparison result. In the compatibility determination process, the comparison result is compared with the interface information of another transmission interface of the second electrical device to obtain a determination result. In the recommendation execution process, a recommendation information is provided according to the determination result.