The invention relates to a continuous evaporation-denitration technology. The technology comprises the following steps that 1, initial denitration material liquid is heated to 90 DEG C to 120 DEG C under negative pressure; 2, a denitration reaction is induced to be conducted, wherein formaldehyde is continuously injected into the heated initial denitration material liquid, sodium nitrite is added to induce the denitration reaction to be conducted, all reaction products flow back while the reaction is induced to be conducted, the temperature is kept at 90 DEG C to 120 DEG C, the denitration reaction induction period is metered by t (the unit is s), and when the denitration reaction induction period t is smaller than 30 s and brown smoke is generated in the reaction, it is determined that the denitration reaction is steadily conducted; 3, continuous evaporation-denitration is conducted, wherein denitration material liquid is continuously injected into the reaction material liquid obtained in the step 2, heating is conducted for continuous evaporation-denitration, and meanwhile mixed gas generated in the reaction is exhausted. According to the technology, the induction period of the formaldehyde denitration reaction can be significantly eliminated, so that stable operation of the continuous evaporation-denitration technology is achieved, pollution of secondary steam is reduced, and the production efficiency is improved.