"代理服务系统" can be translated into English as "Proxy Service System".
Alternatively, depending on the specific context and technical details, it could also be expressed as:
"Agency Service System" (if emphasizing the role of an agent or intermediary)
"Surrogate Service System" (though less common, it can convey the idea of a substitute or representative service)
However, "Proxy Service System" is the most straightforward and commonly used translation in technical and IT contexts.