The present invention provides a modified corn cob cultivation matrix including the following component raw materials: in volume ratio, 55-65 parts of modified corn cob, 10-15 parts of perlite, 10-15 parts of vermiculite powder, 10-15 parts of peat and 5-10 parts of modified plant ash. During preparation, firstly, plant ash and corn cob are modified, and then mixed with other components according to the requirements of the formula. The cultivation matrix of the present invention is reasonable in raw material ratio, is prepared by modifying the plant ash and meanwhile using an enzymic method to modify corn cob fiber, so that the sponginess, air permeability, water retention, heat and moisture retention and nutrient content of the prepared cultivation matrix are improved significantly, the plant ash is modified for granulation, so that the flying property and alkalinity of the plant ash can be effectively improved, the windage loss of the plant ash is reduced, the economic benefits of the utilization of waste products can be realized, the prepared cultivation matrix is suitable for cultivation of various plants, the transplanting survival rate is high, the slow seedling time after transplanting is short, the survival rate is high, and the incidence of diseases and insect pests is low.