Abstract: With the method of comparison,the relations among load of NbCl₅,inside temperature,purity of NbCl₅,carrying methods of argon gas and average flux of NbCl₅ were roundly studied.And the effect of flux of NbCl₅ on felting of materials,quality of spreading niobium and using rate of NbCl₅ was analyzed.The problems such as controlling difficulty of flux of NbCl₅ and felting of materials were solved.The results show that the carrier gas should not pass the inside of the vaporing pot and the heating curve should be confirmed by load of NbCl₅ and heating characteristics,for controlling the flux relatively stably.And the early flux of NbCl₅ shall be small,and then enlarges very slowly in the process of spreading niobium.The average flux is about 260 g/h.In this way,materials do not felt,and both of quality of tiny spheres and using rate of NbCl₅can be ensured.