In this work, we present a systematic study of the observed isoscalar tensor $f_2$ states. With the detailed analysis of the mass spectrum and calculation of the $f_2$ two-body strong decays, we extract information of their underly structures, and try to categorize them into the conventional tensor meson family ($n^{3}P_{2}$ $(n=1,2,3,4)$ and $m^{3}F_{2}$ ($m=1,2$)). We also give predictions for other decay modes of these tensor mesons, which are useful for further experimental investigations., Comment: 12 pages, 3 tables and 10 figures. More discussions and references added. Accepted by Phys. Rev. D