Objective: The content and categories of alkaloids in the combination of Radix Aconiti Lateralis Preparata with different prepared products of Pinellia Rhizoma were studied by electrospray ionization mass spectrometry (ESI-MS). Method: The samples for ESI-MS study were prepared by decocting a mixture of Radix Aconiti Lateralis Preparata

Radix Aconiti Lateralis Preparata with unprocessed Rhizoma Pinelliae

prepared Rhizoma Pinellize with juice of Rhizima zingiberis recens

prepared Rhizoma Pinellize without adjuvant and Rhizoma pinelliae preparatum. Result: Comparing to unprocessed Rhizoma Pinelliae

the content of diester diterpenoid alkaloids was higher in the decoction of Radix Aconiti Lateralis Preparata with prepared Rhizoma Pinellize without adjuvant

prepared Rhizoma Pinellize with juice of Rhizima zingiberis recens and unprocessed Rhizoma Pinelliae

and lower in the decoction of Radix Aconiti Lateralis Preparata with rhizoma pinelliae preparatum. Comclusion: For the hydrolysis and pyrolysis of alkaloids are inhibited;and lower in the decoction of Radix Aconiti Lateralis Preparata with Rhizoma pinelliae preparatum.

for most of diester diterpenoid alkaloids are hydrolyzed.