Abstract: In the light of physical properties, grain-size analysis and thin-section examination, the optimal scaling regression analysis is introduced in the applications to the quantitative analysis of main controlling factors of reservoir porosity development in the second to fourth members of the Shahejie Formation in the Puwei region, Dongpu depression, Shandong. The results of research indicate that the multivariate influencing factors of reservoir porosity development can be simply and rapidly judged by the optimal scaling regression analysis. These influencing factors include oil grades, stratigraphic horizons, cement contents, relationship between the reservoir rocks and gypsolith, porosity reduction by compaction, and sorting coefficients. In the early stages of diagenesis, the sorting determines the initial porosity of reservoir rocks, and compaction is the main reason for the reduction of reservoir porosity. Till the middle and late stages of diagenesis, the hydrocarbon charging contributes a lot to the preservation of reservoir porosity.