AIM: Agricultural and industrial wastes, such as deteriorated corns and oil foots, were used as slow-release materials to prepare biodegradable puffed fertilizers, with urea was encapsulated in fertilizer particles with three-dimensional (3D) skeleton construction.METHODS: Slow-release materials formed 3D skeleton construction through modified treatments, swelling, comminution,extrusion and pelleting. Also 3D skeleton construction and its scales were modified by alternating technical conditions,species and ratio of materials in order to realize the controlled-release of fertilizers.RESULTS: Puffed slow-release fertilizers were prepared. And 3D skeleton construction formed as a compact protective layer on surface of fertilizer particles, whose coating fraction of urea was larger than 85%, the number of pin hole (larger than 20 nm) was lower than 20%, and thickness of membrane was larger than 30 nm. The protective layers of samples in soil were biodegraded and pulled out by microbes. Therefore fertilizer particles emerged gradually and dissolved into soil. Slow release of puffed fertilizers was a continuous process containing degradation, abscission and dissolution. And the whole procedure did not yield any polluting residuals. Release experiments in water showed that pure urea (100%) dissolved absolutely in 10 minutes, whereas only 8.2% urea was released from samples with urea content 85.50% after 120 minutes.And similar experiments in soil illuminated that 85% urea was dissolved from pure urea (100%) in 20 hours, whereas 1.3% and 0.8% urea was released from puffed slow-release fertilizers with urea content 81.5% and 40.9% respectively. Therefore,the release rate of slow-release puffed fertilizers was only 1/65.38 and 1/106.25 to that of pure urea.CONCLUSION: Compared with pure urea, the release rates of puffed slow-release fertilizers in both water and soil are apparently low. Furthermore, puffed slow-release fertilizers have good biodegradability (＞95%), which can improve the construction of soil and increase the content of organic fertilizers.