The invention relates to a cross-platform intelligent data transmission method and belongs to the field of intelligent transmission of a power system. The cross-platform intelligent transmission is performed by combining an FTP technology with an ETL technology. The method comprises the following main steps of (1) obtaining external weather data information from a wide area network through an external data interface; (2) through a reverse isolation writing technology, writing the external weather data into a specified internal network sharing position; (3) performing intelligent transmission through a timed task scheduling function in a data intelligent transmission module; (4) extracting the weather data and other power related data to a business application data storage server according to requirements; and (5) carrying out businesses of line loss computation, power stealing analysis prediction and the like based on the weather data and the power information collection data of application data storage, archive data, power stealing case data and the like by business demand personnel. Therefore, the problems of low efficiency and poor security in the prior art are solved.