Abstract: Research on development physiology of Chinese fir (Cunninghamia lanceolata) seeds and causes of formation of abortive seeds showed that,with embryo differentiating and developing,female germanium and embryo increased their dry weight,volume and biological macromolecules (DNA,RNA,proteins,liquids) till seed matured.The abortive seeds contained lectins.This matter played a role in forming storage protein,independent of abortion.The abortive seeds only accumulated large abscises acid,which caused the abortion and inactivation.From the results of investigation,some measures of decreasing abortion rate were proposed.