Large-array BIB detectors have been the subject of extensive research due to their high quantum efficiency and low dark current， particularly for space applications such as the JWST， which was launched in 2021 and has made numerous significant astronomical observations. A stable， efficient， and lightweight temperature zone liquid helium cryogenic system is essential to the operation of the BIB detectors. The helium JT cryocooler is a trend that aims to meet the cooling requirements of a liquid helium temperature zone in space while supplanting the traditional， large-volume liquid helium dewar. To simultaneously increase the cooling capacity at 4.2 K and reduce its weight， a high-capacity， lightweight 4.2 K cryocooler with a cooling power of 0.3 [email protected] K is proposed. Experiments on the previous 0.1 W at 4.1 K prototype of the cryogenic system have validated the system''s design method. Different cooling methods are used in different cooling temperature zones to achieve the efficiency and lightness of cooling. A new integrated Stirling cryocooler was developed to provide efficient pre-cooling at 80 K， with a cooling capacity of 15 W and a weight of only 4.5 kg. A 0.9 W at 15 K active piston phase-shifting pulse tube cryocooler is used to improve the efficiency of the second-stage pre-cooling. The developing cryogenic system can provide a cooling capacity of 0.3 W at 4.2 K with a power consumption of less than 1.8 kW by coupling the helium JT cycle. It will provide the essential guarantee for the large-scale BIB detection required for infrared astronomical observation， which is undergoing rapid development.