Abstarct: Iron is an essential trace element in human nutrition that its deficiency is to lead the most common nutritional deficiency in the world such as anemia, mental retardation, reduction in growth rate and increasing the risk of dying in childbirth. Iron encapsulation is an effective method to improve its biological efficiency such as insolubility, controlled delivery (in given amount and place) and prevention of side complications. In this research production of cold-treat soy protein isolate nanogel in transport and release of iron have been studied. To find optimal conditions for production of cold-set gel, soy protein isolate solution heated at different temperatures (80-120°C) and times (20-180 min) and different concentrations of Calcium Chloride (5-50 mM). The best conditions in terms of temperature and concentration were 120 oC and 20 mM respectively. According to the results variation of time had no effect on gel's properties. The size of nanogel particles was determined using a static light scattering. The results showed that ultrasound method at a frequency of 20 kHz, constant power of 90 W and an amplitude of 75% is used to produce a gel with107 nm particle size. About gels appearance, results showed that increasing in iron caused to increase L* value while L* and a* factor of nanogels decreased due to particle size reduction. Under the circumstance, efficient encapsulation and capability of soy protein were to keep iron bound in any condition. The increase in iron concentration leads to increase in encapsulation efficiency as it raised from 78% to 94.8%. Compertivetily higher content of the iron released in simulated intestinal condition (89.3%) that was considerbley more than simulated gastric condition (19.7%). The texture of the gels were evaluated by using texture analyzer. Results obtained with the TPA showed that cohesiveness increased with higher iron concentration while hardness, chewiness, springiness, guminess and adhesiveness decreased. Key words: