Adding impurity elements into diamond can obtain other properties on the basis of retaining its original excellent properties, for example, doping boron element can make diamond become P-type semiconductor. Co-doping other elements can improve the electrical properties and catalytic activity of diamond, and even change the conductive mechanism of boron-doped diamond films. In this paper, the preparation methods, structural characteristics and micro-morphology of boron and its co-doped diamond films are introduced in detail. The factors affecting the properties of boron and its co-doped diamond films and the modification methods are summarized.