NOVELTY - Producing antiviral medicament ribavirin using Bacillus amyloliquefaciens, precursor addition and fermentation method, comprises constructing genetically engineered strain RBVM (pBSA43-Bs816PNP) with high-efficient nucleoside production and purine nucleoside phosphorylase expression characteristics, adding 1,2,4-triazole-3-carboxy formamide (TCA) precursor and producing ribavirin through fermentation. The method specifically comprises e.g. constructing secretory expression vector pBSA43-Bs816PNP and engineering strain RBVM (pBSA43 Bs816PNP), culturing, adding TCA and fermenting.    USE - The method is useful for producing antiviral medicament ribavirin using Bacillus amyloliquefaciens, precursor addition and fermentation method (claimed).    ADVANTAGE - The method has short fermentation period, high yield, high glycoside conversion rate, and simple techniques; is economical; consumes less energy; and reduces the pollution.    DETAILED DESCRIPTION - Producing antiviral medicament ribavirin using Bacillus amyloliquefaciens, precursor addition and fermentation method, comprises self-constructing genetically engineered bacteria RBVM (pBSA43-Bs816PNP) with high-efficient nucleoside production and high-efficient purine nucleoside phosphorylase expression characteristics, adding 1,2,4-triazole-3-carboxy formamide (TCA) precursor and producing ribavirin through fermentation. The method specifically comprises (i) utilizing molecular biology technology, taking guanosine-producing bacteria Bacillus amyloliquefaciens TA208 as a host strain, constructing genetically engineered bacteria RBVM (pBSA43-Bs816PNP) with efficient expression of purine nucleoside phosphorylase (PNPase): i.e. amplifying low molecular weight purine nucleoside phosphorylase gene pupG By PCR from Bacillus subtilis BS168, transforming with modified expression vector PBSA43 to construct high expression efficiency and high plasmid stability secretory expression vector pBSA43-Bs816PNP and engineering strain RBVM (pBSA43 Bs816PNP), and (ii) carrying out amplification culture of strain RBVM (pBSA43-Bs816PNP) by adding it into the fermentation culture medium, adding precursor and fermenting, where the carbon source content in fermenting culture medium is 8-12%, the nitrogen to carbon ratio N:C is 10:100-15:100, the inorganic salt content is 0.1-12%, the fermentation culture medium initial pH is 7.2-7.8, the culture temperature is 33-35 degrees C, oscillation-culturing or fermentation tank culturing is carried out for 60-80 hours, the inoculation quantity is 5-10% (vol./vol.), in the fermentation process, adding aqueous ammonia to adjust the pH value of the fermentation liquid to 7-7.4, fermenting for 12-24 hours and adding TCA.