Abstract: Through the determination of photosynthetic characteristics physiological indexes and formaldehyde content in leaves of Sansevieria thunb,Chlorophytum comosum,Chamaedorea elegans,Spathiphyllum floribundum and Hedera helix,the periodic physiology of phytoremediation for formaldehyde was analyzed and discussed.The result showed that: the diurnal variations of formaldehyde content in plants presented as that achieved the highest at about 8:00,then gradually decreased with the lapse of time,and reached the lowest at about 12:00,after gradually increased with the time expand.The relationship with photosynthetic characteristics manifested as that with the improving of Pn,Tr,Ci,Gs declined and the reducing ascended,with the reducing of Ls declined and the improving ascended,and the effect of WuE on the diurnal variations of formaldehyde content in plants was not obvious.With the changing of photosynthetic characteristics,the daily average content of formaldehyde demonstrated wave properties.The partial regression and correlation analysis showed that the formaldehyde content in leaves of Sansevieria thumb was related to Tr,Ls,Ci,with the partial regression very significant;the formaldehyde content in leaves of Chlorophytum comosum had relation to Pn,Ls,Ci of partial regression very significant,and Gs of significant;the formaldehyde content in leaves of Chamaedorea elegans was related to Pn,Gs,WuE,with the partial regression very significant,while Ls,Ci significant;the formaldehyde content in leaves of Spathiphyllum floribundum had relation to Tr,Pn,Gs of partial regression very significant,and Ci,WuE of significant;the formaldehyde content in leaves of Hedera helix was related to Tr,Ci,Gs,with the partial regression very significant,while Pn,Ls significant.It can be seen that the period of phytoremediation for formaldehyde was related to photosynthetic physiology of plants.