Thin films of Bi7Fe3Ti3O21, Bi7Fe3Ti3O21, and Bi6.15Sm0.85Fe2CoTi3O21 are prepared on Pt/Ti/SiO2/Si (100) substrates by using a chemical solution deposition route and the magnetic and ferroelectric properties are investigated. Thin film of Bi7Fe3Ti3O21 shows robust ferroelectric polarization loop compared with ceramics, signal crystal and thin films reported before. The room-temperature ferromagnetism is clearly observed in the films of Bi7Fe3Ti3O21 and Bi(6.15S)m(0.85)Fe(2)CoTi(3)O(21), while the Bi7Fe3Ti3O21 film shows the paramagnetic behavior at room temperature. The Co-doped sample exhibits a high remnant magnetization Mr of 2.67 emu/cm(3) and remnant polarization Pr of 19.2 mu C/cm(2). The ferromagnetism can be ascribed to the spin canting of Fe- and Co-based sublattices via the Dzyaloshinskii-Moriya interaction and the ferrimagnetic ordering of transition metals. The improvement of the P-r and M-r are discussed in terms of growth grain size, reduce grain boundary, and the variation of intergrain connectivity caused by Co- and Sm-doping.