Igneous rocks are widely developed in the Permian system in Taipen area of Tarim Oilfield. The length of open hole in second section cementing is long (5000 ~ 7000 m) and the leakage pressure is low (1.30 ~ 1.40 g/cm3). When using traditional low density cement slurry, the success rate of one-time up-return is not high, only about 30%. The reverse squeezing remedial measures after leakage often cause formation leak off near the surface casing shoe, forming a large section of empty casing, resulting in a low qualified rate of overall cementing. To solve these problems, an ultra-low density cement slurry with a density of 1.20 g/cm3 was developed. The cement slurry has the advantages of stable performance in the high temperature and high pressure environment of the long open hole section, rapid strength development under large temperature difference of top 80 °C, and high early strength. It has been applied in 4 wells on site, the average cementing qualification rate is 92%. The total application effect is good, which can well meet the cementing requirements of different blocks and different temperature and pressure conditions in the Permian strata of the Tarim Oilfield and provide technical support for the safe and efficient development of oil and gas reservoirs.