Abstract: Many discovered petroleum mainly develop in the deeply-buried Jurassic and Cretaceous sandstone reservoirs in the center of Junggar Basin and intergranular secondary porosity develop at the depth of 3 500~6 200 m belong to a stage of late diagenesis. The porosity is about 4%~20% resulting from organic acid that generates from hydrocarbon maturation dissolving carbonate cements and silicate. According to the relationship among temperature, depth and Ro (vitrinite reflectance), there exists the other small scale secondary porosity band vertically resulting from organic acid dissolving ferro carbonate cements at the depth of 6 500 m.