The invention belongs to the technical field of mass spectrometric analysis and test, specifically to a desolvation and ionizationoun method through heating and an apparatus. The desolvation and ionizationoun method includes atomizing a sample to be tested, and heating the atomized liquid drops or particles of the sample through flame to be tested to evaporate solvent of ion sources and ionize neutral molecules. In this way, the gas phase sample ions are obtained. The apparatus comprises a sample atomizing device, a flame generator etc. The sample to be tested forms electriferous or neutral mist-like liquid drops at the outlet of an ion source sample atomizing device, solvent evaporation occurs to the electriferous or neutral mist-like liquid drops of the object to be analyzed when heated by flame to generate gas phase ions of which the mass spectrum can be detected, and proton-exchange reaction occurs to the neutral sample molecules and ions generated by flame to generate sample ions. The thermotropic solvent evaporation or proton-exchange reaction substantially improves the ionizationoun efficiency in the sample to be tested, the ion signal intensity of the sample is increased, and the sensitivity of mass spectrometry is effective improved.