Abstract: Diverse amino acids produce different signal responses with disparate ionization. Accordingly, none of the currently available mass spectrometric techniques can analyze all amino acids simultaneously. Here, it was a better way that combination of electrospray ionization(ESI), atmospheric pressure chemical ionization(APCI) and atmospheric pressure photo ionization(APPI) enhanced ionization efficiency for amino acids. The results show that the application of multiple ionization mass spectrometry is expected to provide a powerful new tool for amino acids research.