The invention discloses a full-washing coal gangue self-thermal insulation building block and a manufacturing method thereof.The full-washing coal gangue self-thermal insulation building block is characterized by being prepared from, by mass, 10-15% of water, 80-88% of washing coal gangue and 2-5% of a pore-forming agent.The manufacturing method comprises the steps of smashing, water adding to achieving uniform stirring, normal-temperature aging, extrusion, slitting, low-temperature drying, high-temperature sintering and the like.The adopted raw materials are convenient to obtain, the burning consumption of the self-thermal insulation building block can be effectively lowered, the production cost is lowered, the mineral waste utilization rate is enlarged, and environmental protection is achieved.The building block is high in strength level and low in density level, water absorption rate and heat transfer coefficient, the requirement for that a public building in a hot summer and cold winter area saves energy by 65%, and the wall heat transfer coefficient is smaller than 1 W(m<2>.k) according to the national building energy-saving design standard can be met, the technology is simple, the production cost is low, popularization and application are easy.