A 2 K heat exchanger is essential for 2 K superfluid helium cryogenic systems, as it increases cooling capacity and improves overall system efficiency. The thermal performance of a 2 K heat exchanger is affected by many factors, such as fluid properties, operating conditions, and geometric parameters. The segmented effectiveness-NTU method approach is used to design the heat exchanger because the physical prosperities of helium vary significantly in the heat exchanger's working temperature, which greatly influences heat transfer characteristics. Meanwhile, the response surface methodology (RSM) is used to optimize the heat exchanger. The optimum combination of geometry parameters is found based on thermal performance and fabrication. According to analyses of single and multiple geometric characteristics by RSM, the tube diameter and fin number have the most significant impact on the heat exchanger performance. Finally, the performance of the heat exchanger is verified experimentally. The experimental results are in good agreement with the present design and optimization model.