By using the different light stimuli, the flash ERG of 32 cases of central retinal vein occlusion(CRVO) (13 of ischemic type,19 of non-ischemic type) during acute phase were examined. The results showed that the a-wave and b-wave latency of CRVO elongated,while the b-wave amplitude of ischemie type decreased and that of non-ischemic type varied in different stimulus: decreased,increased or normal.Therefore,b-wave amplitude and b/a ratio,and selection of suitable ERG condition of stimulus are thought to be important in differetiating ischemic from non-ischemic CRVO. (Chin J Ocul Fundus Dis,1994,10:7-10）