The exploratory experiments of precipitating vanadium which simulated the process conditions in a vanadium plant with the indexes of vanadium loss and the cost were tested with industrial sulfuric acid and flue-gas sulfuric acid in laboratory, respectively. The technology optimizations were studied by selecting the experimental group with the lowest vanadium loss and cost. The results indicate that the vanadium loss and cost are the lowest by one-step vanadium precipitation with flue-gas sulfuric acid, and the optimum processes are as follows: the pH of solution is adjusted to 2.2 after adding the vanadium precipitation agent; the precipitation is proceeded 1 hour at 99°C or 100°C. The vanadium loss and cost per 1000 kg V2O3 are respectively 3.06 kg and 763.18 yuan by the optimum processes, which are much less than the processes with industrial sulfuric acid.