Male butterflies have some certain pathways to prevent the female butterfly which has mated with them from mating with other butterflies. Research shows that some proteins from the male butterflies may play an important role in this mechanism. To investigate how the pathway works, the proteins contained in the spermatophore which is injected into the female butterfly by the male one during mating are very important. In this study, the butterfly spermatophore proteins were mainly studied. The proper procedures to obtain the spermatophore from the female body were developed. Since capillary electrophoresis (CE) has many advantages for separation and detection of low amounts of sample, it was used in this study in order to separate the proteins obtained from spermatophores. Finally, Mass Spectrometry (MS) was performed to analyze the proteins after separation in order to identify the proteins. This thesis mainly introduced the following points: 1. The method for obtaining spermatophores from butterfly bodies and the procedures for extracting proteins from spermatophores. 2. Optimized methods and conditions of Capillary Zone Electrophoresis (CZE) for butterfly spermatophore proteins. Several CZE methods and sets of conditions were compared in order to find the optimized ones. 3. Protein samples were applied to Mass Spectrometry (MS) to try to analyze and identify them. Moreover, the effect of using ZiptipsTM for sample pretreatment was discussed.