4-fluorophthalimide is an important intermediate for fluorophthalocyanines, but it has not been large-scale commercial produced and the price is high. 4-fluorophthalimide was synthesized with 4-nitrophthalimide by Balz-Schieman method in this paper. The relationship between yield of the diazotization and fluoroboric acid was investigated and the yield could reach 89.23%. The effect of reaction conditions, such as reaction mode, feeding mode, catalyst, reaction time and temperature, on the yield of the thermal decomposition were also investigated and the yield could reach 43.35％. Compared with the way using 4-fluorophthalic anhydride as raw materials, the method reported in this paper reduced cost a lot and is applicable for industrial production.