The invention relates to a low-cost smelting technology of a converter, which belongs to the field of steel smelting. According to the smelting technology, a converter oxygen blowing process is divided into two stages, wherein in the first stage of high-efficiency dephosphorization, the oxygen blowing amount is controlled to be 13-18 Nm<3> each ton of iron, part of phosphorus-rich slag is poured out after the blowing, and 3-5 kg each ton of iron of sludge pellets are added when the blowing of the gun stops, thereby ensuring favoring slag pouring and the slag pouring rate of 40%-80%; in the second stage of less slag decarburization stage, a slag remaining and steel tapping mode is adopted at the terminal point of converter blowing. According to the smelting technology provided by the invention, converter lime is consumed at 10-20 kg each ton of steel, light burned dolomite is consumed at 5-12 kg each ton of steel, the phosphorus content of terminal molten steel can be steadily controlled to be below 0.013%, and the dephosphorization rate in the converter process is above 85%. Compared with the prior art, low-cost smelting technology has the beneficial effects that the use amounts of the converter lime and the light burned dolomite are reduced by 30%-50%, the consumption of the converter steel material is reduced by 5-6 kg each ton of steel, and the converter smelting cost is greatly reduced.