Grid computing is a kind of distributed computing paradigm, with its goal to share the resources (CPU, memory, etc.,) among virtual organizations. In the latest researches, open grid services architecture (OGSA) develops and deploys the grid service in a fixed node, and the requester calls the grid service by use of RPC. The drawbacks of this static approach are obvious, such as continuous connection, waste of bandwidth, less intelligence and overloaded with services invocation. Aiming at the drawbacks of such a static model, a mobile agent-based grid mobile service is presented and researched in our lab. The general objective of this paper is to show a bottom implementation of mobile agent-based of code-uploading in the computation grid by use of the cross-platform feature of Java program. Meanwhile, the details of design and implementation are presented. The execution results show the feasibility of our new thoughts about the mobile agent-based grid mobile service.