To increase the COP of small cryogenic refrigerators which have a reciprocating expander, it is needed to reduce shuttle loss. The shuttle loss consists of the following two factors; shuttle heat transfer and gas pressure cycling. In this report only the shuttle heat transfer was investigated, and new analyses for the shuttle heat transfer were presented by taking into account various phase differences and effective heat-transfer area. Based on results of the analyses and numerical solution, a new method to reduce the shuttle heat transfer was proposed. To discuss totally shuttle loss in the refrigerators, the effect of gas pressure cycling must be further incorporated into the analyses.