Crocodile blood is a waste material in slaughtering of crocodile industry.Recently, it was added value as a supplemented food product and now popular for consumption. In the future, if the demand of crocodile blood material increase, it may not adequate for supplying. Therefore, the blood collection process on animal life maintain of captive Siamese crocodile (Crocodylus siamensis) was developed. By collecting the anterior dorsal sinus blood in a 100 milliliters volume from 9 crocodiles,there were divided into 3 groups according to the duration time in each crocodile blood collection as following. The crocodiles that had blood collection every 4 weeks, 8 weeks and 12 weeks, respectively. And the control crocodile group (n = 3), blood collecting in a 5 milliliters volume were taken every 4 weeks. The results were evaluated by crocodile blood donor behavior i.e. food feeding and social behaviors, determination of hematological and biochemical values, and the concentration of cortisol hormone. These data indicated that the duration time in each blood collection should more than 8 weeks. However, the optimum duration time for crocodile blood collection process remained to be elucidated.