Abstract: A control rod driving mechanism, comprising a sealing shell assembly, a travel casing fixedly connected to the sealing shell assembly, a coil assembly sleeved on the sealing shell assembly, and a hook assembly disposed in the sealing shell assembly, wherein the sealing shell assembly comprises a sealing shell and a tube base, and the sealing shell and the tube base form an integral structure. The integral structure eliminates the process for welding the tube base to the sealing shell. In this way, the time for manufacturing and assembling the overall reactor might be saved. Also, compared with the prior art, the reactor employing such scheme would reduce one nuclear first class weld, lowering the risk of leakage. In sum, the structure described above extends the service life of the control rod driving mechanism, and remarkably decreases the work for in-service inspection of the control rod driving mechanism.