The invention discloses an organic fertilizer or a bio-mixed organic fertilizer special for rice and a preparing method thereof. The organic fertilizer or the bio-mixed organic fertilizer special for rice is prepared by composting and fermenting raw materials (dry basis) according to the following weight percentage: 10%-20% of straw stalks, 25%-30% of rice chaff (bran), 25%-35% of rapeseed cakes (dregs), 5%-20% of sugar refinery filtered mud, 5%-10% of bagasse ash and 0.1% of ferment bacterial fertilizer. The organic fertilizer or the bio-mixed organic fertilizer is good in fertilizer effect and environment-friendly, can lead nutritional components absorbed by rice, rape and sugarcanes from the soil to return to the land so as to restore soil fertility, leads circular economy to be developed, use quantity of fertilizers and pesticides are reduced, green and organic agricultural products are produced, production cost and environment cost are reduced, food safety is improved, environment is protected, and modern agriculture and green agriculture development are promoted.