On the basis of sedimentary environment background in the north China, the authors consider that depositional environment in the Huanghua and Jizhong depressions was the shallow-sea of continental margin at early Paleozoic. According to fossil assemblage and rock-electric features as well as standard sequence of lower Paleozoic in the Jizhong depression, we classify the Lower Paleozoic sequences in the drilled well of Nanpu sag, and set up the standard sequence of Lower Paleozoic in the Nanpu sag. The distribution range of upper Majiagou, lower Majiagou and Cambrian sequences was interpreted by well-seismic calibration.