Blazar is an extreme subset of AGNs，constituting less than a few percent of the known AGN population. While Blazar have some properties in common with other AGNs，they have some characteristics that set them apart. The observation properties are probably the cause of strong beaming effect，and these properties would be mutually correlated. The relationship between the polarization and the magnitude variation in brightness，as well as the core-dominance parameter are derived and used statistically to compare with the observational data of Blazar smaples. The result suggests that the polarization, variation and the core-dominance parameters are possible indications of the beaming effect.