To evaluate the relationship between the level of transforming growth factor-beta1 (TGF-beta1) in serum of patients with nonproliferation diabetic retinopathy and the severity of this retinopathy, and to find out a new method for early intervention of diabetic retinopathy.TGF-beta1 in serum was measured in the three groups as following: group DR containing the patients with nonproliferation diabetic retinopathy identified by funds fluorescein angiography, group DM consisting of diabetic without diabetic retinopathy, and group C containing healthy people, and analysed statistically. Then the patients with diabetic retinopathy were divided into three subgroups based on the phase of retinopathy: DR1, DR2, DR3, which results were also analysed statistically.The level of TGF-beta1 in serum had no significant difference between the group DM and group C, and the level of the group DR was higher than group DM or the group C significantly. The level of the group DR1 was lower than the group DR2 DR3 significantly.In patients with nonproliferation diabetic retinopathy, the level of TGF-beta1, in serum is increased, and can reflect the severity of diabetic retinopathy. The level of TGF-beta1 in serum can also indicate the time of intervention to a certain extent.