The encysted dormant Artemis salina embryos were discovered being at their blastula stage through paraffin section. The encysted and decapsulated Artemla embryos hydrated for a short time were successfully cryopreserved in liquid nitrogen with various concentrations of glycerol, DMSO, glucose and sucrose as cryoprotectants, but cryoprotectants were found having no cryoprotection for embryos which were hydrated fully and developed to late developmental stages. Dual cryoprotectants (glycerol+DMSO, glucose+sucrose) had stronger cryoprotections than single-type cryoprotectants. Saturated NaCl solution showed a powerful eryoprotection for various developmental stages of Artemia embryos, although having a weaker cryoprotection for later developmental stages. The author suggested water in embryos related to freezing damage. That freezing was lethal to the later develop mental stages was possibly because of intramembranous ice formation. Cryoprotectant toxicity, hypertonic solution effect and freezing tolerance were determined for various developmental stages of mitten crabs. One-cell embryo was sensitive to glycerol and hypertonic solution, multicell embryo was also sensitive to hypertonic solution. DMSO and methanol had little toxicity to mitten crab embryos under the condition we used. One-cell and multicell embryos were the the most sensitive to freezing. Quarter embryo was the most tolerant to freezing. The addition of cryoprotectants to the chilled solution improved the freezing tolerance of various developmental stages. Yolk was seriously damaged especially in one-cell and multicell embryos which died after freezing. Author suggested that the damage was an important reason resulting in freezing death of early embryos. Glycerol DMSO, glucose, and sucrose were found improving tolerance of Artemia nauplii to freezing. Freezed to -30 ℃ for 9-10 minutes in 20% glycerol, more than 80% of nauplii survived. DMSO, methanol and glycerol possessed some cryoprotections for Eriocheir sinensiszoea. Freezed to -24 ℃ for 8-9 minutes in 20% methanol, more than 70% of zoea survived.