Nowadays, people nutrition pattern is turned to using cereals without bran, processed meat products and foods with high percentage of fat and sugar. This new and widening procedure is the reason of obesity increasing and spreading of some chronic diseases like diabetes, heart disease, and some cancers. So, the tendency to use low fat food is so obvious among consumers. Removing food fat leads to undesirable sensory and performance characteristics. Thus, different compounds have been introduced as fat replacer in order to reach low fat food products. The aim of this study was to reduce the used fat in sausage production by using emulsion filled gel. So, in the first step, production of emulsion filled gel based on rice bran oil and inulin using ultrasonic waves was optimized in terms of its stability and consistency and then, rosemary essential oil was added to used oil in production of optimized emulsion filled gel and the properties of the oil of emulsion filled gel including peroxide value, thiobabituric acid value, total phenolic compounds, antioxidant property and polar compounds were evaluated. In the second step, the fat of frankfurter sausage formulation was substituted with emulsion filled gel as fat replacer at the rates of 0, 50 and 100 percent and the properties of produced low fat sausage were evaluated in terms of chemical compounds, pH, textural properties, color, porosity, cooking loss, water holding capacity and sensory characteristics. Based on descriptive models, using 18% rice bran oil, 44.6% inulin and 256 W power of ultrasonic leads to production of emulsion filled gel with 99.95% stability and 290.8 N.s consistency. Results showed the effect of ultrasonic waves on oil oxidation and rosemary essential oil had meaningful effect on prevention of oil oxidation. Also, total phenolic compounds and DPPH free radical scavenging ability were decreased after ultrasonic process. Results showed that ultrasonic waves not only causes active free radicals production but also decreases the antioxidant properties of compounds, which leads to oxidation and degradation of emulsion filled gel oil. Results of sausages showed that the sausage containing emulsion filled gel has higher moisture, ash, pH, water holding capacity and porosity. As by increasing the substitution percent, these factors have been also increased. On the other hand, fat content, cooking loss, cutting force and textural properties (hardness, cohesiveness, gumminess, chewiness) except springiness of low fat sausages have been decreased. Emulsion filled gel darkened the sausages and by increasing the substitution percent, L (brightness) and a (redness) were decreased and b (yellowness) was increased. Sausages sensory evaluation showed that increasing of substitution percent of emulsion filled gel couldn't lead to decrease of product color. Also, the sausage containing 50% emulsion filled gel had better texture in comparison with two other samples. Totally, using emulsion filled gel in low fat sausage production could not cause meaningful effect on consumers general accept of this product. So, it is possible to produce a low fat product with good qualitative and nutritional properties by substitution of the used oil in sausage production with emulsion filled gel. Keywords: fat replacer, emusion filled gel, inulin, low fat sausage.