The mobile agent paradigm has revealed many security concerns: how to protect mobile agents from malicious hosts or how to protect benign hosts from baleful agents, etc. This greatly limits its proliferation in the marketplace. In this paper, we propose a novel approach named PICC (Partly Iterative Crypto-Computing) to support autonomous mobile agent to accomplish secure computation on untrusty hosts. The basic tool in PICC is garbled circuit. The main advantage of PICC is that it provides a way to evaluate a Boolean function with cipher-text input directly without decrypting them first. The output of Boolean function is also in cipher-text form and can be fed back as a new input of next round secure computation. PICC makes it possible that mobile agents move autonomously and fulfill the secure computation without interacting with the agents? originator.