The invention discloses a machining technology of a steel-wrapped-steel heat preservation steam steel pipe, and relates to the technical field of heat preservation steel pipes. The machining technology comprises the first step of inner steel pipe and outer steel pipe machining, the second step of foam aluminum-magnesium foaming forming and the third step of foam aluminum-magnesium filling. According to the machining technology, an aluminum ingot serves a main material, a magnesium ingot serves as an auxiliary material, foam aluminum-magnesium is prepared with assistance of ceramic micro powder, glass fiber powder, nano zinc oxide, nano barium carbonate, a foaming agent and lanthanum oxide, and the steel-wrapped-steel heat preservation steam steel pipe is prepared through the prepared foamaluminum-magnesium filling. The foam aluminum-magnesium serves as filler for endowing the steam steel pipe with excellent heat preservation performance, the foam magnesium-aluminum is light, the heatconduction coefficient is small, and recycling can be achieved.