The unreasonable use of crop straw will not only waste a lot of resources,but also cause serious damage tothe atmospheric environment by greenhouse gases produced by direct burning.In this study,the total amount ofstraw resources of main crops was estimated through the statistics of crop cultivation in 17 cities of Shandong Prov-ince in 2017.This paper evaluates straw fertilization on soil N,P,K and organic matter supplementation,and con-structs the mathematical model of straw fuelling utilization and carbon emission,and obtains the total amount of bio-gas produced by bio-fermentation of crop straw.Carbon emissions after combustion and utilization were assessed toprovide reference for carbon emission reduction of straw biogas.The results showed that the total amount of straw inShandong Province in 2017 was 6 433.66×10⁴t,and the nutrients of fertilized returned straw could replace 64.77×10⁴t of CO（NH₂）₂,34.16×10⁴t of Ca（H₂PO₄）₂ and 81.02×10⁴ t of K₂SO₄.A total of 835.50×10⁴t of organic matterwas immobilized by soil.The straw could produce 17 288.25×10⁵m³ of biogas which can replace 1.23×10⁶t ofstandard coal,and reduced 240.43×10⁴t of CO₂ compared with straw direct burning.