This paper preliminarily reports the robotic system working inside the gantry of vertical field Open MRI. This manipulator is new in terms of the application to vertical field Open MRI, cost effectiveness,accuracy and stiffness sufficient for endoscope manipulation. The endoscope manipulation for trans-nasal neurosurgery under MR-guidance was selected as the sample task. The endoscope operation in MR-gantry might provide the surgeon(s) with real-time feedback of MR image to endoscopic image and the reverse. This facilitates the comprehensive understanding, because MRI compensates the vision lost through narrow opening of keyhole surgery with global view. So this surgery is a good motivation for combination of MRI and robotic systems. In this paper, the design and implementation are presented and preliminary test shows good MR-compatibility, accuracy and stiffness.