The invention discloses a catalyst for oxosynthesis of methylacrolein through isobutene and a preparation method thereof and belongs to the technical field of fine chemical engineering. The preparation method specifically includes following steps: adding ammonium molybdate, cerous nitrate and other metal salt into a container with water for dissolving to obtain a mixed solution; weighing needed ammonia water, and adding deionized water into the ammonia water to dilute the same by 2-4 times; using a constant-temperature magnetic stirrer to stir the mixed solution for 30-120min, and dropwise adding diluted ammonia water liquid into the mixed solution during stirring; putting turbid liquid in a rotary evaporator at temperature of 80-90 DEG C for rotary evaporation for 1-4h to evaporate away excessive moisture; putting size in an oven at temperature of 80-120 DEG C for drying for 3-18h; putting a catalyst half-finished product in a muffle furnace at temperature of 400-800 DEG C for roasting for 4-12h to obtain the catalyst. The preparation method is simple, and the catalyst prepared by the method is high in catalytic efficiency, so that the preparation method is suitable for popularization in the field of chemical engineering.