The purpose of this study was to suggest a new detection method for early diagnosing diabetic neuropathic foot by obtaining a ratio of toe to finger blood flow using photoplethysmography(PPG) and Laser Doppler(LD). Nerve conduction velocity (NCV) has been routinely used for diagnosing neuropathic foot, but it applies strong electric stimulus to peripheries resulting in stress and pain. The blood flow ratio of 50 neuropathic diabetes(0.96±0.20) was significantly higher than that of 64 normal person(0.46±0.15)(p<0.000). It also showed that toe temperature of neuropathic diabetes(30.5±1.4℃) was significantly higher than that of normal group(29.3±2.0℃)(p<0.000). The optimal boundary value of the blood flow ratio was found to be 0.678 and the sensitivity and specificity of this proposed method resulted in 95.3% and 95.3% respectively. Lastly, there were no neuropathic diabetes whose temperature difference between finger and toe was higher than 4.5 ℃.