This paper optimized the fixing procedure of the routine paraffin section technology and observed the process of adventitious rooting development of three culture rooting seedlings of Eucalyptus clones ‘DH3229’, ‘GL9’ and ‘XF35’. The results showed that: (1) FAA fixing solution was better with clear staining and tissue integrity root slice on Eucalyptus. (2) Adventitious roots of ‘DH3229’ and ‘GL9’ originated after 8 days being induced and belongs to cortices rooting type. Adventitious roots of ‘XF35’ originated after 12 days being inducted and belongs to callus rooting type. Activedivision cells are in root tip and root foundation of ‘GL9’ adventitious root. Activedivision cells are only in root tip of ‘DH3229’ adventitious root. Activedivision cells are only in root foundation of ‘XF35’ adventitious root.