This invention relates to downdraft gasification method and equipment for preparing tar-free product gas by oxygen-deficient fluidized burning. The equipment comprised a front fluidized bed burner, a downdraft fixed bed gasifier set lower than the burner, a transporting pipe for carbocoal and semi-finished gas connecting the burner and the gasifying furnace, a fuel inlet and an oxidant inlet. The method comprised: (1) adding fuel through the fuel inlet of the fluidized bed burner, and performing oxygen-deficient fluidized burning with oxidant added through the oxidant inlet at the bottom of the fluidized bed burner to obtain carbocoal and semi-finished gas containing tar, and (2) sending the unseparated carbooal and semi-finished gas containing tar to a down-draft fixed bed gasifier at a high temperature to gasify the carbocoal, and modifying and cracking the tar introduced by the semi-finished gas by the catalytic activity of high-temperature carbocoal to obtain the product gas with tar. The equipment has such advantages as simple structure, easy operation and high gasifying efficiency, and is suitable for a wide variety of fuels and can produce product gas without tar. |