The performance of an MR JT (Mixed Refrigerant Joule-Thomson) refrigerator is greatly affected by the heat exchanger performance such as pressure drop and effectiveness. The heat exchanger design, therefore, is very important in the development of an MR JT refrigerator. In this paper, the recuperative heat exchanger design for the MR JT refrigerator is investigated with the experimental results. The heat exchangers of different geometry are fabricated. Their performances are investigated in the cryogenic helium test facility. The MR JT refrigeration system is constructed to examine the mixed refrigerant characteristics at low temperature. The non-flammable and environmentally-friendly mixed refrigerant is blended and adopted for the MR JT refrigerator. The fabricated heat exchangers show sufficient thermal performance to reach the cold-end temperature of around 140 K. The experimental results are presented and discussed with the comparison of helium tests and MR JT refrigerator tests.