The invention discloses a detection method and device for photovoltaic string connection. The method includes generating configuration files of strings of an inverter in a subarray and an inverter port, wherein the configuration files are used for recording the corresponding relation between the port of the inverter and the strings; after the subarray is mounted successfully, collecting power generation information of the strings of the inverter in the subarray; comparing the collected power generation information with the configuration files and detecting whether the connection of the strings in the subarray is normal or not. According to the invention, problem of insufficient connection and error connection between the photovoltaic strings and a DC combiner box/inverter can be detected automatically.