A wide range tunable magnetic lens for the desktop electron microscope is provided. The wired range tunable magnetic lens comprises a coil support, an inner pole piece, a permanent-magnet, a first outer pole piece and a second outer pole piece. The inner pole piece covers the coil support and forms a first magnetic-circuit gap. The permanent-magnet forms a ring structure according to the central axis and is disposed at the outer side of the inner pole piece away from the central axis. The first outer pole piece is adjacently disposed at the upper-side of the permanent-magnet and extends to the central hole of the coil support. The second outer pole piece is adjacently disposed at the under-side of the permanent-magnet and extends to the central hole of the coil support, wherein the first outer pole piece and the second outer pole piece forms a second magnetic-circuit gap.