The invention provides a novel titanate capable of being used as a lithium ion secondary battery cathode active material. The general formula of the active material is Li2+xSrmM1-mTi5+nN1-nO14-y, wherein M is one or the combination selected from Al, Ba, Ca, Ce, Cs, La, Mg, K, Na, Sr, Mn and Sn, N is one or the combination selected from Mn, Ti, Co, Zr and V, x is greater than or equal to 0 and is less than or equal to 0.5, m is greater than or equal to 0 and is less than or equal to 1, n is greater than or equal to 0 and less than or equal to 1, and y is greater than or equal to 0 and is less than or equal to 1. The Li+/Li operating voltage from the material is 0.8-1.45V, and the metal Li potential is low compared with a lithium titanate material; when the novel titanate is paired with lithium manganate or cobalt acid lithium, the operation voltage higher than that of a battery taking lithium titanate as a negative electrode is obtained, and the safety problem of battery short circuit due to formation of lithium dendrites caused by separation of lithium metal is solved.