The invention discloses an IGCC (Integrated Gasification Combined Cycle) poly-generation device and method based on pyrolysis and gasification of low metamorphic powdered coal. The device comprises a pyrolysis/gasification system, a coal gas purifying system, a circulating fluidized bed boiler and a gas turbine/steam turbine system. The method comprises the steps as follows: carrying out low temperature pyrolysis and partial air gasification on the low metamorphic powdered coal, grading and converting into coal gas, tar and semi-coke, and carrying out the IGCC poly-generation process by the semi-coke and the coal gas with high calorific value. According to the device and the method, the tar, sulphur and other chemical products can be produced while clean power is generated, the products obtained by grading and converting the low metamorphic powdered coal are fully utilized, the material conversion and energy conversion functions are integrated, the resource utilization rate is high, and the heat energy efficiency is high. The device and method are suitable for the low metamorphic powdered coal such as peat, brown coal, jet coal, non-sticking coal and the like, and the particle size of raw materials is 0-8 mm. The high-temperature coal gas generated in a fluidized bed gasification furnace contains a large amount of hydrogen, so that the powdered coal can be subjected to hydropyrolysis, and the tar recovery rate can reach more than 12%.