Abstract:The effects of pollen water content, thawing treatments, duration of storage in liquid nitrogen (LN) and pollen contacting with LN directly on viability of pollen of Eucommia ulmoides Oliv. and Sinojackia xylocarpa Hu. stored in LN were studied systematically. Also, the possibility of using differential thermal analysis (DTA) to determine the scope of the water content within which the pollen could store in LN safely was tested. The results indicated that among the factors affecting the pollen cryopreservation in LN, pollen water content was the major one. It may be promising to introduce DTA to pollen cryopreservation.