Abstract: The room temperature multiferroic material La₂Ti_2-xCo_xO₇ (x=0, 0.03, 0.05, 0.07) is successfully synthesized by introducing magnetic Co ions into La₂Ti₂O₇. The microstructural investigation indicates that all the samples crystalize into a single phase structure and no impurity can be observed in the detected range of the X-ray diffraction. A suitable concentration of Co doping could not only enhance the magnetism, but also decrease the leakage current and increase the insulativity. As a result, the ferroelectricity and multiferroic can be improved. Simultaneously, the ferromagnetic, antiferromagnetic and paramagnetic interactions in La₂Ti_2-xCo_xO₇ are also discussed. The ferromagnetism originates from the coupling interaction of the oxygen vacancies and the spins of Co cations. For the undoped La₂Ti₂O₇ samples, the ferromagnetism can be attributed to the oxygen vacancies. For keeping the balance of the valence, the existed oxygen vacancies cause that some Ti⁴⁺ ions are transformed into Ti³⁺ ions. Therefore, an electron exists in the 3d orbital of Ti³⁺ ions and weak ferromagnetism emerges in La₂Ti₂O₇ sample.