Blending controlled release urea BB fertilizer

The invention relates to a controllable releasing urea BB fertilizer, which in detail a mixed long effective urea fertilizer, comprising three urea components A, B, and C; said A is normal urea, B and C are capsule urea added with urea-formaldehyde resin, the weight proportion of urea-formaldehyde resin in B and C are 2-5 % and 6-10% of that of urea respectively; the ratio by weight among A, B and C is 1-2: 2-3: 5-6. The invention is characterized by good effect, high utilization rate and simple process.