Abstract: In this study,it was discovered by means of various temperature treatments within the temp,range of effective development (7-40C) that the larvae,pupae and eggs of silkworm had their TRCD,which were 22~27C,22~27C and 23~27C respectively.TRCD maybe one of the intrinsic variety characteristics of the silkworm.Since it could not be described by former mathematical models,a study to design a new one will be necessary.